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170-487: Plateosaurus (probably meaning "broad lizard ", often mistranslated as "flat lizard") is a genus of plateosaurid dinosaur that lived during the Late Triassic period , around 214 to 204 million years ago , in what is now Central and Northern Europe. Plateosaurus is a basal (early) sauropodomorph dinosaur, a so-called "prosauropod" . The type species is Plateosaurus trossingensis ; before 2019, that honor

340-695: A Compsognathus longipes fossil was found with a lizard in its stomach, and a Velociraptor mongoliensis specimen was found locked in combat with a Protoceratops andrewsi (a type of ornithischian dinosaur). The first confirmed non-carnivorous fossil theropods found were the therizinosaurs , originally known as "segnosaurs". First thought to be prosauropods , these enigmatic dinosaurs were later proven to be highly specialized, herbivorous theropods. Therizinosaurs possessed large abdomens for processing plant food, and small heads with beaks and leaf-shaped teeth. Further study of maniraptoran theropods and their relationships showed that therizinosaurs were not

510-461: A 1999 paper by Paul Sereno suggests that theropods are characterized by traits such as an ectopterygoid fossa (a depression around the ectopterygoid bone), an intramandibular joint located within the lower jaw, and extreme internal cavitation within the bones. However, since taxa like Herrerasaurus may not be theropods, these traits may have been more widely distributed among early saurischians rather than being unique to theropods. Instead, taxa with

680-489: A branch and stays perfectly still, with only its eyes moving. When an insect lands, the chameleon focuses its eyes on the target and slowly moves toward it before projecting its long sticky tongue which, when hauled back, brings the attached prey with it. Geckos feed on crickets , beetles, termites and moths . Termites are an important part of the diets of some species of Autarchoglossa, since, as social insects , they can be found in large numbers in one spot. Ants may form

850-530: A computed tomography scan and 3D reconstruction software. These finds are of evolutionary significance because they help document the emergence of the neurology of modern birds from that of earlier reptiles. An increase in the proportion of the brain occupied by the cerebrum seems to have occurred with the advent of the Coelurosauria and "continued throughout the evolution of maniraptorans and early birds." Studies show that theropods had very sensitive snouts. It

1020-542: A cutting edge similar to those of extant herbivorous or omnivorous reptiles. Paul Barrett proposed that prosauropods supplemented their mostly herbivorous diets with small prey or carrion , thus making them omnivores. So far, no fossil of Plateosaurus has been found with gastroliths ( gizzard stones) in the stomach area. The old, widely cited idea that all large dinosaurs, implicitly also Plateosaurus , swallowed gastroliths to digest food because of their relatively limited ability to deal with food orally has been refuted by

1190-430: A detailed description of Plateosaurus with illustrations, but again gave no details on the etymology. He repeatedly referred to its gigantic size ("Riesensaurus" = giant lizard) and massive limbs ("schwerfüssig"), comparing Plateosaurus to large modern land mammals, but did not describe any important features that fit the terms "flat" or "shaped like an oar." Researcher Ben Creisler therefore concluded that "broad lizard"

1360-422: A doubled clitoris. The majority of species are oviparous (egg laying). The female deposits the eggs in a protective structure like a nest or crevice or simply on the ground. Depending on the species, clutch size can vary from 4–5 percent of the females body weight to 40–50 percent and clutches range from one or a few large eggs to dozens of small ones. In most lizards, the eggs have leathery shells to allow for

1530-579: A few centimeters long to the 3-meter-long Komodo dragon . Most lizards are quadrupedal, running with a strong side-to-side motion. Some lineages (known as " legless lizards ") have secondarily lost their legs, and have long snake-like bodies. Some lizards, such as the forest-dwelling Draco , are able to glide. They are often territorial , the males fighting off other males and signalling, often with bright colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators ; many smaller species eat insects, while

1700-633: A fossil they believed to be plant material. The drill core containing the fossil was extracted from 2,256 m (7,402 ft) below the seafloor. Martin Sander and Nicole Klein, palaeontologists of the University of Bonn , analysed the bone microstructure and concluded that the rock preserved fibrous bone tissue from a fragment of a limb bone belonging to Plateosaurus , making it the first dinosaur found in Norway. Material referred to Plateosaurus has also been found in

1870-447: A gigantic Saurian, which, in virtue of the mass and hollowness of its limb-bones, is allied to Iguanodon and to Megalosaurus , and will belong to the second division of my Saurian system." Von Meyer later gave the formal name Pachypodes or Pachypoda ("thick feet") to his second division of "Saurians with Limbs Similar to Heavy Land Mammalia", but the group was a synonym of Richard Owen's Dinosauria from 1842. In 1855, von Meyer published

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2040-416: A group including the relatively derived theropod subgroups Ceratosauria and Tetanurae , and excluding coelophysoids . However, most later researchers have used it to denote a broader group. Neotheropoda was first defined as a clade by Paul Sereno in 1998 as Coelophysis plus modern birds , which includes almost all theropods except the most primitive species. Dilophosauridae was formerly considered

2210-452: A higher probability of being within the Theropoda may share more specific traits, such as a prominent promaxillary fenestra, cervical vertebrae with pleurocoels in the anterior part of the centrum leading to a more pneumatic neck, five or more sacral vertebrae, enlargement of the carpal bone, and a distally concave portion of the tibia, among a few other traits found throughout the skeleton. Like

2380-555: A limited ability to regulate their body temperature, and must seek out and bask in sunlight to gain enough heat to become fully active. Thermoregulation behavior can be beneficial in the short term for lizards as it allows the ability to buffer environmental variation and endure climate warming. In high altitudes, the Podarcis hispaniscus responds to higher temperature with a darker dorsal coloration to prevent UV-radiation and background matching. Their thermoregulatory mechanisms also allow

2550-487: A long, flexible neck, sharp but plump plant-crushing teeth, powerful hind limbs, short but muscular arms and grasping hands with large claws on three fingers, possibly used for defence and feeding. Unusually for a dinosaur, Plateosaurus showed strong developmental plasticity: instead of having a fairly uniform adult size, fully grown individuals were between 4.8 and 10 metres (16 and 33 ft) long and weighed between 600 and 4,000 kilograms (1,300 and 8,800 lb). Commonly,

2720-422: A partial sacrum (series of fused hip vertebrae) as a lectotype . The type locality is not known for certain, but Moser attempted to infer it from previous publications and the colour and preservation of the bones. He concluded that the material probably stems from the "Buchenbühl", roughly two kilometres (1.2 mi) south of Heroldsberg. The type specimen of Plateosaurus gracilis , an incomplete postcranium ,

2890-406: A plethora of synonyms (invalid duplicate names) at the genus level. Discovered in 1834 by Johann Friedrich Engelhardt and described three years later by Hermann von Meyer , Plateosaurus was the fifth named dinosaur genus that is still considered valid. Although it had been described before Richard Owen formally named Dinosauria in 1842, it was not one of the three genera used by Owen to define

3060-567: A pouch beneath its eyes, to a distance of about two metres (6.6 feet); the blood tastes foul to these attackers. The closest living relatives of lizards are rhynchocephalians , a once diverse order of reptiles, of which is there is now only one living species, the tuatara of New Zealand. Some reptiles from the Early and Middle Triassic , like Sophineta and Megachirella , are suggested to be stem-group squamates, more closely related to modern lizards than rhynchocephalians, however, their position

3230-463: A predator that has caught them; attempt to outrun the rattlesnake , which does not pursue prey; but stay still, relying on their cryptic coloration, for Masticophis whip snakes which can catch even swift prey. If caught, some species such as the greater short-horned lizard puff themselves up, making their bodies hard for a narrow-mouthed predator like a whip snake to swallow. Finally, horned lizards can squirt blood at cat and dog predators from

3400-430: A prominent part of the diet of some lizards, particularly among the lacertas. Horned lizards are also well known for specializing on ants. Due to their small size and indigestible chitin , ants must be consumed in large amounts, and ant-eating lizards have larger stomachs than even herbivorous ones. Species of skink and alligator lizards eat snails and their power jaws and molar-like teeth are adapted for breaking

3570-416: A relationships between tooth size and skull length and also a comparison of the degree of wear of the teeth of non-avian theropods and modern lepidosaurs , it is concluded that theropods had lips that protected their teeth from the outside. Visually, the snouts of such theropods as Daspletosaurus had more similarities with lizards than crocodilians, which lack lips. Tyrannosaurus was for many decades

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3740-603: A relatively long lower leg, an elongated metatarsus and a digitigrade foot posture. However, in contrast to mammalian cursors, the moment arms of the limb extending muscles are short, especially in the ankle, where a distinct, moment arm-increasing tuber on the calcaneum is missing. This means that in contrast to running mammals, Plateosaurus probably did not use gaits with aerial, unsupported phases. Instead, Plateosaurus must have increased speed by using higher stride frequencies, created by rapid and powerful limb retraction. Reliance on limb retraction instead of extension

3910-428: A result of growth or seasonal changes, which can be used to approximate age at the time of death. However, the amount of rings in a skeleton can vary from bone to bone, and old rings can also be lost at advanced age, so scientists need to properly control these two possibly confounding variables. Body mass is harder to determine as bone mass only represents a small proportion of the total body mass of animals. One method

4080-427: A revision of the material. The skull of AMNH FARB 6810, the best-preserved skull of Plateosaurus that has been taken apart during preparation and is thus available as separate bones, was described anew in 2011. The authors of that publication, palaeontologists Albert Prieto-Márquez and Mark A. Norell, refer the skull to P. erlenbergensis , a species erected in 1905 by Friedrich von Huene and regarded as

4250-416: A sauropod-like growth pattern, initially rapid, then slowing after sexual maturity, and almost, but not fully, stopping in old age. However, their initial growth rate is much lower than in mammals, birds and dinosaurs. The reptilian growth rate is also very variable, so that individuals of the same age may have very different sizes, and final size also varies significantly. In extant animals, this growth pattern

4420-410: A shift in the use of the forearm, with greater flexibility at the shoulder allowing the arm to be raised towards the horizontal plane, and to even greater degrees in flying birds. However, in coelurosaurs, such as ornithomimosaurs and especially dromaeosaurids, the hand itself had lost most flexibility, with highly inflexible fingers. Dromaeosaurids and other maniraptorans also showed increased mobility at

4590-478: A side-branch of more advanced theropods, they may have been ancestral to all other theropods (which would make them a paraphyletic group). Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs , and is the only group of theropods that survived the Triassic–Jurassic extinction event . Neotheropoda was named by R.T. Bakker in 1986 as

4760-472: A single clade , the Toxicofera ). However, most of these putative venom genes were "housekeeping genes" found in all cells and tissues, including skin and cloacal scent glands. The genes in question may thus be evolutionary precursors of venom genes. Recent studies (2013 and 2014) on the lung anatomy of the savannah monitor and green iguana found them to have a unidirectional airflow system, which involves

4930-425: A single unit with little flexibility. In theropods and prosauropods, the only way for the palm to face the ground would have been by lateral splaying of the entire forelimb, as in a bird raising its wing. In carnosaurs like Acrocanthosaurus , the hand itself retained a relatively high degree of flexibility, with mobile fingers. This was also true of more basal theropods, such as herrerasaurs . Coelurosaurs showed

5100-525: A small clade within Neotheropoda, but was later considered to be paraphyletic . By the Early Jurassic , all non-averostran neotheropods had gone extinct. Averostra (or "bird snouts") is a clade within Neotheropoda that includes most theropod dinosaurs , namely Ceratosauria and Tetanurae . It represents the only group of post-Early Jurassic theropods. One important diagnostic feature of Averostra

5270-700: A species affects the structure of territories, for example, rock lizards have territories atop rocky outcrops. Some species may aggregate in groups, enhancing vigilance and lessening the risk of predation for individuals, particularly for juveniles. Agonistic behaviour typically occurs between sexually mature males over territory or mates and may involve displays, posturing, chasing, grappling and biting. Lizards signal both to attract mates and to intimidate rivals. Visual displays include body postures and inflation, push-ups, bright colours, mouth gapings and tail waggings. Male anoles and iguanas have dewlaps or skin flaps which come in various sizes, colours and patterns and

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5440-483: A study on gastrolith abundance, weight, and surface structure in fossils compared to alligators and ostriches by Oliver Wings. The use of gastroliths for digestion seems to have developed on the line from basal theropods to birds, with a parallel development in Psittacosaurus . Similar to all non-avian dinosaurs studied to date, Plateosaurus grew in a pattern that is unlike that of both extant mammals and birds. In

5610-531: A synonym of P. engelhardti by Markus Moser. If the P. erlenbergensis holotype is diagnostic (i.e., has enough characters to be distinct from other material), it is the correct name for the material assigned to P. longiceps Jaekel, 1913. Aside from fossils clearly belonging to Plateosaurus , there is much prosauropod material from the German Knollenmergel in museum collections, most of it labeled as Plateosaurus , that does not belong to

5780-461: A total of 35 complete or partially complete skeletons of Plateosaurus , as well as fragmentary remains of approximately 70 more individuals. The large number of specimens from Swabia had already caused German palaeontologist Friedrich August von Quenstedt to nickname the animal Schwäbischer Lindwurm (Swabian lindworm or Swabian dragon ). Much of the Trossingen material was destroyed in 1944, when

5950-423: A variety of different camouflage methods . Many lizards are disruptively patterned . In some species, such as Aegean wall lizards , individuals vary in colour, and select rocks which best match their own colour to minimise the risk of being detected by predators. The Moorish gecko is able to change colour for camouflage: when a light-coloured gecko is placed on a dark surface, it darkens within an hour to match

6120-406: A wide variety of tasks (see below). In modern birds, the body is typically held in a somewhat upright position, with the upper leg (femur) held parallel to the spine and with the forward force of locomotion generated at the knee. Scientists are not certain how far back in the theropod family tree this type of posture and locomotion extends. Non-avian theropods were first recognized as bipedal during

6290-557: Is Halberstadt, located in Saxony-Anhalt and the Trossingen Formation . The etymology of the name Plateosaurus is not entirely clear, as the original description contains no information and various authors have offered differing interpretations. German geologist Hanns Bruno Geinitz in 1846 gave "( πλᾰτῠ́ς , breit)" [English: broad] as the origin of the name, with von Meyer's Latin spelling Plateosaurus evidently derived from

6460-563: Is a member of a group of early herbivores known as " prosauropods ". The group is not a monophyletic group (thus given in quotation marks), and most researchers prefer the term basal sauropodomorph . Plateosaurus was the first "prosauropod" to be described, and gives its name to the family Plateosauridae as the type genus . Initially, when the genus was poorly known, it was only included in Sauria , being some kind of reptile, but not in any more narrowly defined taxon. In 1845, von Meyer created

6630-409: Is a typical value for birds, but not for mammals, and indicates that Plateosaurus probably had an avian -style flow-through lung, although indicators for postcranial pneumaticity (air sacs of the lung invading the bones to reduce weight) can be found on the bones of only a few individuals, and were only recognised in 2010. Combined with evidence from bone histology this indicates that Plateosaurus

6800-468: Is also believed to have also been different among different families. The spinosaurids could have used their powerful forelimbs to hold fish. Some small maniraptorans such as scansoriopterygids are believed to have used their forelimbs to climb in trees . The wings of modern birds are used primarily for flight, though they are adapted for other purposes in certain groups. For example, aquatic birds such as penguins use their wings as flippers. Contrary to

6970-482: Is an extant dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous , although a number of theropod groups evolved to become herbivores and omnivores . Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago ( Ma ) and included

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7140-422: Is based on genomic analysis by Wiens and colleagues in 2012 and 2016. Excluded taxa are shown in upper case on the cladogram. Dibamidae Diplodactylidae [REDACTED] Theropod Theropoda ( / θ ɪəˈr ɒ p ə d ə / ; from ancient Greek θηρίο- ποδός [ θηρίον , ( therion ) "wild beast"; πούς , ποδός ( pous, podos ) "foot"]) whose members are known as theropods ,

7310-621: Is disputed, with some studies recovering them as less closely related to squamates than rhynchocephalians are. The oldest undisputed lizards date to the Middle Jurassic, from remains found In Europe, Asia and North Africa. Lizard morphological and ecological diversity substantially increased over the course of the Cretaceous . In the Palaeogene , lizard body sizes in North America peaked during

7480-423: Is itself a junior synonym of P. engelhardti . Furthermore, a variety of species in other genera were created for material belonging to P. engelhardti , including Dimodosaurus poligniensis , Gresslyosaurus robustus , Gresslyosaurus torgeri , Pachysaurus ajax , Pachysaurus giganteus , Pachysaurus magnus and Pachysaurus wetzelianus . G. ingens has been considered separate from Plateosaurus , pending

7650-606: Is kept at the Staatliches Museum für Naturkunde Stuttgart , Germany, and the type locality is Heslach, a suburb of the same city. The type specimen of Plateosaurus trossingensis is SMNS 132000, stored in the same museum as P. gracilis . Its type locality is Trossingen, within the Trossingen Formation . The type specimen of Plateosaurus longiceps is MB R.1937, which is stored in the Museum für Naturkunde in Berlin. Its type locality

7820-467: Is known as the extant-scaling (ES) approach. A second method, known as the volumetric-density (VD) approach, uses full-scale models of skeletons to make inferences about potential mass. The ES approach is better for wide-range studies including many specimens and doesn't require as much of a complete skeleton as the VD approach, but the VD approach allows scientists to better answer more physiological questions about

7990-666: Is known to occur in various species of whiptail lizards . Parthenogenesis was also recorded in species that normally reproduce sexually. A captive female Komodo dragon produced a clutch of eggs, despite being separated from males for over two years. Sex determination in lizards can be temperature-dependent . The temperature of the eggs' micro-environment can determine the sex of the hatched young: low temperature incubation produces more females while higher temperatures produce more males. However, some lizards have sex chromosomes and both male heterogamety (XY and XXY) and female heterogamety (ZW) occur. A significant component of aging in

8160-541: Is linked to behavioural thermoregulation and a low metabolic rate (i.e. ectothermy ), and is called "developmental plasticity". (Note that is not the same as neural developmental plasticity ). Plateosaurus followed a trajectory similar to sauropods, but with a varied growth rate and final size as seen in extant reptiles, probably in response to environmental factors such as food availability. Some individuals were fully grown at only 4.8 metres' (16 ft) total length, while others reached 10 metres (33 ft). However,

8330-551: Is probably another junior synonym of Plateosaurus . Basal sauropodomorph phylogeny simplified after Yates, 2007. This is only one of many proposed cladograms for basal sauropodomorphs. Some researchers do not agree that plateosaurs were the direct ancestors of sauropods. Unaysaurus Plateosaurus Riojasaurus Eucnemesaurus Massospondylus   Coloradisaurus   Lufengosaurus   Jingshanosaurus Anchisauria Practically every imaginable posture has been suggested for Plateosaurus in

8500-512: Is suggested they might have been used for temperature detection, feeding behavior, and wave detection. Shortened forelimbs in relation to hind legs was a common trait among theropods, most notably in the abelisaurids (such as Carnotaurus ) and the tyrannosaurids (such as Tyrannosaurus ). This trait was, however, not universal: spinosaurids had well developed forelimbs, as did many coelurosaurs. The relatively robust forelimbs of one genus, Xuanhanosaurus , led D. Zhiming to suggest that

8670-565: Is the absence of the fifth metacarpal. Other saurischians retained this bone, albeit in a significantly reduced form. The somewhat more advanced ceratosaurs (including Ceratosaurus and Carnotaurus ) appeared during the Early Jurassic and continued through to the Late Jurassic in Laurasia . They competed alongside their more anatomically advanced tetanuran relatives and—in the form of

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8840-478: Is the avian-style lung of Plateosaurus . Long-bone histology also allows estimating the age a specific individual reached. Sander and Klein found that some individuals were fully grown at 12 years of age, others were still slowly growing at 20 years, and one individual was still growing rapidly at 18 years. The oldest individual found was 27 years and still growing; most individuals were between 12 and 20 years old. However, some may well have lived much longer, because

9010-412: Is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians ), encompassing over 7,000 species , ranging across all continents except Antarctica , as well as most oceanic island chains . The grouping is paraphyletic as some lizards are more closely related to snakes than they are to other lizards. Lizards range in size from chameleons and geckos

9180-604: Is the most suitable translation, and possibly was intended to emphasise the giant size of the animal, in particular its robust limb bones. Von Meyer had authored a popular audience book in 1852 Ueber Die Reptilien und Säugethiere Der Verschiedenen Zeiten Der Erde [On the Reptiles and Mammals from the Different Time Periods of the Earth] based to two public lectures. In the book on page 44, he briefly described Plateosaurus , using

9350-408: Is to measure the circumference of the femur, which in non-avian theropod dinosaurs has been shown to be a relatively proportional to quadrupedal mammals, and use this measurement as a function of body weight, as the proportions of long bones like the femur grow proportionately with body mass. The method of using extant animal bone proportion to body mass ratios to make predictions about extinct animals

9520-443: Is typical for non-avian dinosaurs. Important cranial characteristics (such as jaw articulation) of most "prosauropods" are closer to those of herbivorous reptiles than those of carnivorous ones, and the shape of the tooth crown is similar to that of modern herbivorous or omnivorous iguanas . The maximum width of the crown was greater than that of the root for the teeth of most "prosauropods", including Plateosaurus ; this results in

9690-592: The Allosauroidea (the diverse carcharodontosaurs ) and the Coelurosauria (a very large and diverse dinosaur group including the birds). Thus, during the late Jurassic, there were no fewer than four distinct lineages of theropods—ceratosaurs, megalosaurs, allosaurs, and coelurosaurs—preying on the abundance of small and large herbivorous dinosaurs. All four groups survived into the Cretaceous, and three of those—the ceratosaurs, coelurosaurs, and allosaurs—survived to end of

9860-647: The Coelophysoidea . The coelophysoids were a group of widely distributed, lightly built and potentially gregarious animals. They included small hunters like Coelophysis and Camposaurus . These successful animals continued from the Late Carnian (early Late Triassic) through to the Toarcian (late Early Jurassic ). Although in the early cladistic classifications they were included under the Ceratosauria and considered

10030-528: The Fleming Fjord Formation of East Greenland, but they were given the new genus name Issi in 2021. The type series of Plateosaurus engelhardti included "roughly 45 bone fragments", of which nearly half are lost. The remaining material is kept in the Institute for Palaeontology of the University of Erlangen-Nuremberg , Germany. From these bones, German palaeontologist Markus Moser in 2003 selected

10200-535: The Keuper stems from the same species as the type material of Plateosaurus engelhardti . However, this is problematic due to the undiagnostic state of the lectotype. Moser considered Sellosaurus to be the same genus as Plateosaurus , but did not discuss whether S. gracilis and P. engelhardti belong to the same species. Palaeontologist Adam Yates of the University of the Witwatersrand cast further doubt on

10370-584: The abelisaur lineage—lasted to the end of the Cretaceous in Gondwana . The Tetanurae are more specialised again than the ceratosaurs. They are subdivided into the basal Megalosauroidea (alternately Spinosauroidea ) and the more derived Avetheropoda . Megalosauridae were primarily Middle Jurassic to Early Cretaceous predators, and their spinosaurid relatives' remains are mostly from Early and Middle Cretaceous rocks. Avetheropoda, as their name indicates, were more closely related to birds and are again divided into

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10540-407: The bee hummingbird ( Mellisuga helenae ) is smallest at 1.9 g and 5.5 cm (2.2 in) long. Recent theories propose that theropod body size shrank continuously over a period of 50 million years, from an average of 163 kilograms (359 lb) down to 0.8 kilograms (1.8 lb), eventually evolving into over 11,000 species of modern birds . This was based on evidence that theropods were

10710-475: The clade Tetanurae for one branch of a basic theropod split with another group, the Ceratosauria. As more information about the link between dinosaurs and birds came to light, the more bird-like theropods were grouped in the clade Maniraptora (also named by Gauthier in 1986 ). These new developments also came with a recognition among most scientists that birds arose directly from maniraptoran theropods and, on

10880-742: The coelurosaurs , feathers may have been confined to the young, smaller species, or limited parts of the animal. Many larger theropods had skin covered in small, bumpy scales. In some species, these were interspersed with larger scales with bony cores, or osteoderms . This type of skin is best known in the ceratosaur Carnotaurus , which has been preserved with extensive skin impressions. The coelurosaur lineages most distant from birds had feathers that were relatively short and composed of simple, possibly branching filaments. Simple filaments are also seen in therizinosaurs, which also possessed large, stiffened "quill"-like feathers. More fully feathered theropods, such as dromaeosaurids , usually retain scales only on

11050-406: The common basilisk , can run across water. Lizards make use of their senses of sight , touch , olfaction and hearing like other vertebrates . The balance of these varies with the habitat of different species; for instance, skinks that live largely covered by loose soil rely heavily on olfaction and touch, while geckos depend largely on acute vision for their ability to hunt and to evaluate

11220-524: The cranium and forelimb, with injuries occurring in about equal frequency at each site. Most pathologies preserved in theropod fossils are the remains of injuries like fractures, pits, and punctures, often likely originating with bites. Some theropod paleopathologies seem to be evidence of infections , which tended to be confined only to small regions of the animal's body. Evidence for congenital malformities have also been found in theropod remains. Such discoveries can provide information useful for understanding

11390-630: The furcula (wishbone), pneumatized bones, brooding of the eggs , and (in coelurosaurs, at least) feathers . O. C. Marsh coined the name Theropoda (meaning "beast feet") in 1881. Marsh initially named Theropoda as a suborder to include the family Allosauridae , but later expanded its scope, re-ranking it as an order to include a wide array of "carnivorous" dinosaur families, including Megalosauridae , Compsognathidae , Ornithomimidae , Plateosauridae and Anchisauridae (now known to be herbivorous sauropodomorphs ) and Hallopodidae (subsequently revealed as relatives of crocodilians). Due to

11560-592: The geckos , anoles , and chameleons , have modified the scales under their toes to form adhesive pads , highly prominent in the first two groups. The pads are composed of millions of tiny setae (hair-like structures) which fit closely to the substrate to adhere using van der Waals forces ; no liquid adhesive is needed. In addition, the toes of chameleons are divided into two opposed groups on each foot ( zygodactyly ), enabling them to perch on branches as birds do. Aside from legless lizards , most lizards are quadrupedal and move using gaits with alternating movement of

11730-485: The microflora necessary for their transition to a plant-based diet. Perhaps the most herbivorous species is the marine iguana which dives 15 m (49 ft) to forage for algae , kelp and other marine plants. Some non-herbivorous species supplement their insect diet with fruit, which is easily digested. Lizards have a variety of antipredator adaptations , including running and climbing, venom , camouflage , tail autotomy , and reflex bleeding . Lizards exploit

11900-455: The spinosaurids ) appear to have specialized in catching fish. Diet is largely deduced by the tooth morphology , tooth marks on bones of the prey, and gut contents. Some theropods, such as Baryonyx , Lourinhanosaurus , ornithomimosaurs, and birds, are known to use gastroliths , or gizzard-stones. The majority of theropod teeth are blade-like, with serration on the edges, called ziphodont. Others are pachydont or folidont depending on

12070-804: The type specimen of a new genus, Plateosaurus . Since then, remains of well over 100 individuals of Plateosaurus have been discovered at various locations throughout Europe. Material assigned to Plateosaurus has been found at over 50 localities in Germany (mainly along the Neckar and Pegnitz river valleys), Switzerland ( Frick ) and France. Three localities are of special importance, because they yielded specimens in large numbers and of unusually good quality: near Halberstadt in Saxony-Anhalt , Germany; Trossingen in Baden-Württemberg , Germany; and Frick. Between

12240-426: The 1910s and 1930s, excavations in a clay pit in Saxony-Anhalt revealed between 39 and 50 skeletons that belonged to Plateosaurus , along with teeth and a small number of bones of the theropod Liliensternus , and two skeletons and some fragments of the turtle Proganochelys . Some of the plateosaur material was assigned to P. longiceps , a species described by palaeontologist Otto Jaekel in 1914. Most of

12410-480: The 19th century, before their relationship to birds was widely accepted. During this period, theropods such as carnosaurs and tyrannosaurids were thought to have walked with vertical femurs and spines in an upright, nearly erect posture, using their long, muscular tails as additional support in a kangaroo-like tripodal stance. Beginning in the 1970s, biomechanical studies of extinct giant theropods cast doubt on this interpretation. Studies of limb bone articulation and

12580-461: The Early Cretaceous. A few palaeontologists, such as Gregory S. Paul , have suggested that some or all of these advanced theropods were actually descended from flying dinosaurs or proto-birds like Archaeopteryx that lost the ability to fly and returned to a terrestrial habitat. The evolution of birds from other theropod dinosaurs has also been reported, with some of the linking features being

12750-653: The Komodo dragon can kill prey as large as water buffalo . Dragons are prolific scavengers , and a single decaying carcass can attract several from 2 km (1.2 mi) away. A 50 kg (110 lb) dragon is capable of consuming a 31 kg (68 lb) carcass in 17 minutes. Around 2 percent of lizard species, including many iguanids, are herbivores. Adults of these species eat plant parts like flowers, leaves, stems and fruit, while juveniles eat more insects. Plant parts can be hard to digest, and, as they get closer to adulthood, juvenile iguanas eat faeces from adults to acquire

12920-432: The Komodo eats mammals as big as water buffalo . Lizards make use of a variety of antipredator adaptations , including venom , camouflage , reflex bleeding , and the ability to sacrifice and regrow their tails . The adult length of species within the suborder ranges from a few centimeters for chameleons such as Brookesia micra and geckos such as Sphaerodactylus ariasae to nearly 3 m (10 ft) in

13090-752: The Naturaliensammlung in Stuttgart (predecessor to the State Museum of Natural History Stuttgart (SMNS)) burnt to the ground after an Allied bombing raid. Luckily, however, a 2011 study by SMNS curator Rainer Schoch found that, at least from the finds of Seemann's 1932 excavation, "the scientifically most valuable material is still available". The Plateosaurus skeletons in a clay pit of the Tonwerke Keller AG in Frick, Switzerland, were first noticed in 1976. While

13260-667: The Order Saurischia into two suborders, Theropoda and Sauropoda. This basic division has survived into modern palaeontology, with the exception of, again, the Prosauropoda, which Romer included as an infraorder of theropods. Romer also maintained a division between Coelurosauria and Carnosauria (which he also ranked as infraorders). This dichotomy was upset by the discovery of Deinonychus and Deinocheirus in 1969, neither of which could be classified easily as "carnosaurs" or "coelurosaurs". In light of these and other discoveries, by

13430-461: The Tetanurae and Ceratosauria. While some used to consider coelophysoids and ceratosaurs to be within the same group due to features such as a fused hip, later studies showed that it is more likely that these were features ancestral to neotheropods and were lost in basal tetanurans. Averostrans and their close relatives are united via the complete loss of any digit V remnants, fewer teeth in the maxilla,

13600-510: The abandonment of ranks in cladistic classification, with the re-evaluation of birds as a subset of theropod dinosaurs that survived the Mesozoic extinctions and lived into the present. The following is a simplified classification of theropod groups based on their evolutionary relationships, and organized based on the list of Mesozoic dinosaur species provided by Holtz. A more detailed version can be found at dinosaur classification . The dagger (†)

13770-439: The air moving in a loop through the lungs when breathing. This was previously thought to only exist in the archosaurs ( crocodilians and birds ). This may be evidence that unidirectional airflow is an ancestral trait in diapsids . As with all amniotes, lizards rely on internal fertilisation and copulation involves the male inserting one of his hemipenes into the female's cloaca . Female lizards also have hemiclitorises ,

13940-546: The animal might have been quadrupedal. However, this is no longer thought to be likely. The hands are also very different among the different groups. The most common form among non-avian theropods is an appendage consisting of three fingers; the digits I, II and III (or possibly II, III and IV ), with sharp claws. Some basal theropods, like most Ceratosaurians , had four digits, and also a reduced metacarpal V (e.g. Dilophosaurus ). The majority of tetanurans had three, but some had even fewer. The forelimbs' scope of use

14110-459: The animal, such as locomotion and center of gravity. The current consensus is that non-avian theropods didn't exhibit a group wide growth rate, but instead had varied rates depending on their size. However, all non-avian theropods had faster growth rates than extant reptiles, even when modern reptiles are scaled up to the large size of some non-avian theropods. As body mass increases, the relative growth rate also increases. This trend may be due to

14280-416: The animals lived for at least 12 to 20 years, but the maximum life span is not known. Despite the great quantity and excellent quality of the fossil material, Plateosaurus was for a long time one of the most misunderstood dinosaurs. Some researchers proposed theories that were later shown to conflict with geological and palaeontological evidence, but have become the paradigm of public opinion. Since 1980

14450-484: The avian theropods (birds). However, discoveries in the late 20th and early 21st centuries showed that a variety of diets existed even in more basal lineages. All early finds of theropod fossils showed them to be primarily carnivorous . Fossilized specimens of early theropods known to scientists in the 19th and early 20th centuries all possessed sharp teeth with serrated edges for cutting flesh, and some specimens even showed direct evidence of predatory behavior. For example,

14620-494: The back. Many researchers were of the opinion that Plateosaurus could use both quadrupedal gaits (for slow speeds) and bipedal gaits (for rapid locomotion), and Wellnhofer insisted that the tail curved strongly downward, making a bipedal posture impossible. However, Moser showed that the tail was in fact straight. The bipedal-quadrupedal consensus was changed by a detailed study of the forelimbs of Plateosaurus by Bonnan and Senter (2007), which clearly showed that Plateosaurus

14790-498: The body. Only a year later, Jaekel instead favoured a clumsy, kangaroo -like hopping, a change of heart for which he was mocked by German zoologist Gustav Tornier, who interpreted the shape of the articulation surfaces in the hip and shoulder as typically reptilian. Fraas, the first excavator of the Trossingen lagerstätte , also favoured a reptilian posture. Müller-Stoll listed a number of characters required for an erect limb posture that Plateosaurus supposedly lacked, concluding that

14960-506: The bone microstructure indicates rapid growth, as in sauropods and extant mammals, which suggests endothermy . Plateosaurus apparently represents an early stage in the development of endothermy, in which endothermy was decoupled from developmental plasticity. This hypothesis is based on a detailed study of Plateosaurus long-bone histology conducted by Martin Sander and Nicole Klein of the University of Bonn. A further indication for endothermy

15130-559: The bones are often significantly deformed by taphonomic processes, Frick yields skeletons of P. trossingensis comparable in completeness and position to those of Trossingen. In 1997, workers of an oil platform of the Snorre oil field , located at the northern end of the North Sea within the Lunde Formation , were drilling through sandstone for oil exploration when they stumbled on

15300-556: The case of the largest living varanid lizard, the Komodo dragon . Most lizards are fairly small animals. Lizards typically have rounded torsos, elevated heads on short necks, four limbs and long tails, although some are legless. Lizards and snakes share a movable quadrate bone , distinguishing them from the rhynchocephalians , which have more rigid diapsid skulls . Some lizards such as chameleons have prehensile tails, assisting them in climbing among vegetation. As in other reptiles,

15470-441: The closely related sauropods with their typical dinosaurian physiology , growth was initially rapid, continuing somewhat more slowly well beyond sexual maturity, but was determinate, i.e. the animals stopped growing at a maximum size. Mammals grow rapidly, but sexual maturity falls typically at the end of the rapid growth phase. In both groups, the final size is relatively constant, with humans atypically variable. Extant reptiles show

15640-498: The day and night, possibly avoiding the midday heat. Plateosaurus gracilis , the older species, is found in the Löwenstein Formation (lower to middle Norian). P. trossingensis and P. longiceps stem from the Trossingen Formation (upper Norian) and equivalently aged rock units. Plateosaurus thus lived probably between approximately 227 and 208.5 million years ago. Lizard Sauria Macartney , 1802 Lizard

15810-499: The different parts of theropod anatomy. The most common sites of preserved injury and disease in theropod dinosaurs are the ribs and tail vertebrae . Despite being abundant in ribs and vertebrae, injuries seem to be "absent... or very rare" on the bodies' primary weight supporting bones like the sacrum , femur , and tibia . The lack of preserved injuries in these bones suggests that they were selected by evolution for resistance to breakage. The least common sites of preserved injury are

15980-500: The distance to their prey before striking. Monitor lizards have acute vision, hearing, and olfactory senses. Some lizards make unusual use of their sense organs: chameleons can steer their eyes in different directions, sometimes providing non-overlapping fields of view, such as forwards and backwards at once. Lizards lack external ears, having instead a circular opening in which the tympanic membrane (eardrum) can be seen. Many species rely on hearing for early warning of predators, and flee at

16150-468: The dorsal (trunk) vertebrae with two joints, acting together as a simple hinge joint, which has allowed researchers to reconstruct the inhaled and exhaled positions of the ribcage. The difference in volume between these two positions defines the air exchange volume (the amount of air moved with each breath), determined to be approximately 20 L for a P. engelhardti individual estimated to have weighed 690 kg, or 29 mL/kg bodyweight. This

16320-421: The early sauropodomorphs, the second digit in a theropod's hand is enlarged. Theropods also have a very well developed ball and socket joint near their neck and head. Most theropods belong to the clade Neotheropoda, characterized by the reduction of several foot bones, thus leaving three toed footprints on the ground when they walk (tridactyl feet). Digit V was reduced to a remnant early in theropod evolution and

16490-586: The environment. The chameleons in general use their ability to change their coloration for signalling rather than camouflage, but some species such as Smith's dwarf chameleon do use active colour change for camouflage purposes. The flat-tail horned lizard 's body is coloured like its desert background, and is flattened and fringed with white scales to minimise its shadow. Many lizards, including geckos and skinks , are capable of shedding their tails ( autotomy ). The detached tail, sometimes brilliantly coloured, continues to writhe after detaching, distracting

16660-601: The evolutionary history of the processes of biological development. Unusual fusions in cranial elements or asymmetries in the same are probably evidence that one is examining the fossils of an extremely old individual rather than a diseased one. The trackway of a swimming theropod, the first in China of the ichnogenus named Characichnos , was discovered at the Feitianshan Formation in Sichuan. These new swim tracks support

16830-454: The exchange of water, although more arid-living species have calcified shells to retain water. Inside the eggs, the embryos use nutrients from the yolk . Parental care is uncommon and the female usually abandons the eggs after laying them. Brooding and protection of eggs do occur in some species. The female prairie skink uses respiratory water loss to maintain the humidity of the eggs which facilitates embryonic development. In lace monitors ,

17000-658: The expansion of the dewlap as well as head-bobs and body movements add to the visual signals. Some species have deep blue dewlaps and communicate with ultraviolet signals. Blue-tongued skinks will flash their tongues as a threat display . Chameleons are known to change their complex colour patterns when communicating, particularly during agonistic encounters. They tend to show brighter colours when displaying aggression and darker colours when they submit or "give up". Several gecko species are brightly coloured; some species tilt their bodies to display their coloration. In certain species, brightly coloured males turn dull when not in

17170-526: The extant non-avian reptiles. Archosauromorpha [REDACTED] [REDACTED] Pantestudines [REDACTED] † Kuehneosauridae [REDACTED] Rhynchocephalia [REDACTED] Squamata [REDACTED] Both the snakes and the Amphisbaenia (worm lizards) are clades deep within the Squamata (the smallest clade that contains all the lizards), so "lizard" is paraphyletic . The cladogram

17340-413: The feet. Some species may have mixed feathers elsewhere on the body as well. Scansoriopteryx preserved scales near the underside of the tail, and Juravenator may have been predominantly scaly with some simple filaments interspersed. On the other hand, some theropods were completely covered with feathers, such as the troodontid Anchiornis , which even had feathers on the feet and toes. Based on

17510-470: The first known dromaeosaurid ( Dromaeosaurus albertensis ) in 1922, W. D. Matthew and Barnum Brown became the first paleontologists to exclude prosauropods from the carnivorous dinosaurs, and attempted to revive the name "Goniopoda" for that group, but other scientists did not accept either of these suggestions. In 1956, "Theropoda" came back into use—as a taxon containing the carnivorous dinosaurs and their descendants—when Alfred Romer re-classified

17680-427: The forelimb), the very limited motion range of the forelimb, and the fact that the centre of mass rests squarely over the hind limbs. A recent study based on the cross-sectional geometry of long limb bones, comparisons with extant taxa and inference models also confirmed a bipedal posture and erect stance for Plateosaurus . Plateosaurus shows a number of cursorial adaptations, including an erect hind limb posture,

17850-500: The fossils from Frick and Trossingen are all animals that died in accidents, and not from old age. Due to the absence of individuals smaller than 4.8 metres (16 ft) long, it is not possible to deduce a complete ontogenetic series for Plateosaurus or determine the growth rate of animals less than 10 years of age. Comparisons between the scleral rings and estimated orbit size of Plateosaurus and modern birds and reptiles suggest that it may have been cathemeral , active throughout

18020-455: The generic separation. He included the type material of Sellosaurus gracilis in Plateosaurus as P. gracilis and reintroduced the old name Efraasia for some material that had been assigned to Sellosaurus . In 1926, von Huene had already concluded the two genera were the same. Yates has cautioned that P. gracilis may be a metataxon, which means that there is neither evidence that

18190-518: The group Pachypodes (a defunct junior synonym of Dinosauria) to include Plateosaurus , Iguanodon , Megalosaurus and Hylaeosaurus . Plateosauridae was proposed by Othniel Charles Marsh in 1895 within Theropoda . Later it was moved to " Prosauropoda " by von Huene, a placement that was accepted by most authors. Before the advent of cladistics in paleontology during the 1980s, with its emphasis on monophyletic groups ( clades ), Plateosauridae

18360-447: The group, because at the time, it was poorly known and difficult to identify as a dinosaur. It is now among the dinosaurs best known to science: over 100 skeletons have been found, some of them nearly complete. The abundance of its fossils in Swabia , Germany, has led to the nickname Schwäbischer Lindwurm (Swabian lindworm ). Plateosaurus was a bipedal herbivore with a small skull on

18530-526: The heaviest theropods known to science. It is still not clear why these animals grew so heavy and bulky compared to the land predators that came before and after them. The largest extant theropod is the common ostrich , up to 2.74 m (9 ft) tall and weighing between 90 and 130 kg (200 - 290 lb). The smallest non-avian theropod known from adult specimens is the troodontid Anchiornis huxleyi , at 110 grams in weight and 34 centimeters (1 ft) in length. When modern birds are included,

18700-608: The hypothesis that theropods were adapted to swimming and capable of traversing moderately deep water. Dinosaur swim tracks are considered to be rare trace fossils, and are among a class of vertebrate swim tracks that also include those of pterosaurs and crocodylomorphs . The study described and analyzed four complete natural molds of theropod foot prints that are now stored at the Huaxia Dinosaur Tracks Research and Development Center (HDT). These dinosaur footprints were in fact claw marks, which suggest that this theropod

18870-419: The jaw joint gave the chewing muscles great leverage, so that Plateosaurus could deliver a powerful bite. These features suggest that it fed primarily to exclusively on plants. Its eyes were directed to the sides, rather than the front, providing all-round vision to watch for predators. Some fossil skeletons have preserved sclerotic rings (rings of bone plates that protect the eye). The ribs were connected to

19040-422: The knee was normally strongly flexed in all theropods while walking, even giants like the tyrannosaurids. It is likely that a wide range of body postures, stances, and gaits existed in the many extinct theropod groups. Although rare, complete casts of theropod endocrania are known from fossils. Theropod endocrania can also be reconstructed from preserved brain cases without damaging valuable specimens by using

19210-442: The known material contains more species belonging to Plateosaurus . Some scientists regard other species as valid as well, for example P. erlenbergensis and P. engelhardti . These claims are problematic since both P. erlenbergensis and P. engelhardti have undiagnostic type specimens. All named species of Plateosaurus except the type species, P. gracilis, or P. longiceps have turned out to be junior synonyms of

19380-544: The largest known theropod and best known to the general public. Since its discovery, however, a number of other giant carnivorous dinosaurs have been described, including Spinosaurus , Carcharodontosaurus , and Giganotosaurus . The original Spinosaurus specimens (as well as newer fossils described in 2006) support the idea that Spinosaurus was probably 3 meters longer than Tyrannosaurus , though Tyrannosaurus might have been more massive than Spinosaurus . Specimens such as Sue and Scotty are both estimated to be

19550-464: The largest living land animal today, the African elephant , which is characterized by a rapid period of growth until maturity, subsequently followed by slowing growth in adulthood. As a hugely diverse group of animals, the posture adopted by theropods likely varied considerably between various lineages through time. All known theropods are bipedal , with the forelimbs reduced in length and specialized for

19720-457: The late 1970s Rinchen Barsbold had created a new series of theropod infraorders: Coelurosauria, Deinonychosauria , Oviraptorosauria , Carnosauria, Ornithomimosauria, and Deinocheirosauria . With the advent of cladistics and phylogenetic nomenclature in the 1980s, and their development in the 1990s and 2000s, a clearer picture of theropod relationships began to emerge. Jacques Gauthier named several major theropod groups in 1986, including

19890-489: The lizard to maintain their ideal body temperature for optimal mobility. Most social interactions among lizards are between breeding individuals. Territoriality is common and is correlated with species that use sit-and-wait hunting strategies. Males establish and maintain territories that contain resources that attract females and which they defend from other males. Important resources include basking, feeding, and nesting sites as well as refuges from predators. The habitat of

20060-421: The lizard-like reconstructions were correct. However, most of these adaptations are actually present in Plateosaurus . From 1980 on, a better understanding of dinosaur biomechanics, and studies by palaeontologists Andreas Christian and Holger Preuschoft on the resistance to bending of the back of Plateosaurus , led to widespread acceptance of an erect, digitigrade limb posture and a roughly horizontal position of

20230-451: The majority of large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous , about 66 Ma. In the Jurassic , birds evolved from small specialized coelurosaurian theropods, and are today represented by about 11,000 living species. Various synapomorphies for Theropoda have been proposed based on which taxa are included in the group. For example,

20400-553: The male tokay gecko is heard as "tokay-tokay!". Tactile communication involves individuals rubbing against each other, either in courtship or in aggression. Some chameleon species communicate with one another by vibrating the substrate that they are standing on, such as a tree branch or leaf. Lizards are found worldwide, excluding the far north and Antarctica, and some islands. They can be found in elevations from sea level to 5,000 m (16,000 ft). They prefer warmer, tropical climates but are adaptable and can live in all but

20570-399: The material assigned to it is monophyletic (belongs to one species), nor that it is paraphyletic (belongs to several species). This is the case because the holotype of P. (Sellosaurus) gracilis has no skull, and the other specimens consist of skulls and material that overlaps too little with the holotype to make it certain that it belongs to the same taxon. It is therefore possible that

20740-588: The material found its way to the Museum für Naturkunde in Berlin, where much of it was destroyed during World War II. The Halberstadt quarry today is covered by a housing development. The second major German locality with Plateosaurus finds, a quarry in Trossingen in the Black Forest , was worked repeatedly in the 20th century. Between 1911 and 1932, excavations during six field seasons led by German palaeontologists Eberhard Fraas (1911–1912), Friedrich von Huene (1921–23), and finally Reinhold Seemann (1932) revealed

20910-495: The middle of the period. Mosasaurs likely evolved from an extinct group of aquatic lizards known as aigialosaurs in the Early Cretaceous . Dolichosauridae is a family of Late Cretaceous aquatic varanoid lizards closely related to the mosasaurs. The position of the lizards and other Squamata among the reptiles was studied using fossil evidence by Rainer Schoch and Hans-Dieter Sues in 2015. Lizards form about 60% of

21080-666: The most extreme environments. Lizards also exploit a number of habitats; most primarily live on the ground, but others may live in rocks, on trees, underground and even in water. The marine iguana is adapted for life in the sea. The majority of lizard species are predatory and the most common prey items are small, terrestrial invertebrates, particularly insects . Many species are sit-and-wait predators though others may be more active foragers. Chameleons prey on numerous insect species, such as beetles , grasshoppers and winged termites as well as spiders . They rely on persistence and ambush to capture these prey. An individual perches on

21250-543: The mouth, and is often long. In the beaded lizards, whiptails and monitor lizards, the tongue is forked and used mainly or exclusively to sense the environment, continually flicking out to sample the environment, and back to transfer molecules to the vomeronasal organ responsible for chemosensation, analogous to but different from smell or taste. In geckos, the tongue is used to lick the eyes clean: they have no eyelids. Chameleons have very long sticky tongues which can be extended rapidly to catch their insect prey. Three lineages,

21420-404: The movement of the tooth row further down the maxilla and a lacrimal fenestra. Averostrans also share features in their hips and teeth. Theropods exhibit a wide range of diets, from insectivores to herbivores and carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of diets was historically considered a characteristic exclusive to

21590-660: The need to reach the size required for reproductive maturity . For example, one of the smallest known theropods was Microraptor zhaoianus , which had a body mass of 200 grams, grew at a rate of approximately 0.33 grams per day. A comparable reptile of the same size grows at half of this rate. The growth rates of medium-sized non-avian theropods (100–1000 kg) approximated those of precocial birds, which are much slower than altricial birds. Large theropods (1500–3500 kg) grew even faster, similar to rates displayed by eutherian mammals. The largest non-avian theropods, like Tyrannosaurus rex had similar growth dynamics to

21760-495: The oldest known bird, Archaeopteryx ), the bird-like troodontids and oviraptorosaurs, the ornithomimosaurs (or "ostrich Dinosaurs"), the strange giant-clawed herbivorous therizinosaurs, and the avialans, which include modern birds and is the only dinosaur lineage to survive the Cretaceous–Paleogene extinction event . While the roots of these various groups are found in the Middle Jurassic, they only became abundant during

21930-537: The oldest pachypode [dinosaur] yet found.] The taxonomic history of Plateosaurus is "long and confusing" and a "chaotic tangle of names". As of 2019, only three species are universally accepted as valid: the type species P. trossingensis, P. longiceps, and P. gracilis , previously assigned to its own genus Sellosaurus . Moser performed the most extensive and detailed investigation of all plateosaurid material from Germany and Switzerland, concluding that all Plateosaurus and most other prosauropod material from

22100-492: The only dinosaurs to get continuously smaller, and that their skeletons changed four times as fast as those of other dinosaur species. In order to estimate the growth rates of theropods, scientists need to calculate both age and body mass of a dinosaur. Both of these measures can only be calculated through fossilized bone and tissue , so regression analysis and extant animal growth rates as proxies are used to make predictions. Fossilized bones exhibit growth rings that appear as

22270-407: The only early members of this group to abandon carnivory. Several other lineages of early maniraptorans show adaptations for an omnivorous diet, including seed-eating (some troodontids ) and insect-eating (many avialans and alvarezsaurs ). Oviraptorosaurs , ornithomimosaurs and advanced troodontids were likely omnivorous as well, and some early theropods (such as Masiakasaurus knopfleri and

22440-441: The only venomous lizards. However, several species of monitor lizards, including the Komodo dragon , produce powerful venom in their oral glands . Lace monitor venom, for instance, causes swift loss of consciousness and extensive bleeding through its pharmacological effects, both lowering blood pressure and preventing blood clotting . Nine classes of toxin known from snakes are produced by lizards. The range of actions provides

22610-460: The painted dragon lizard Ctenophorus pictus is fading breeding colors. By manipulating superoxide levels (using a superoxide dismutase mimetic) it was shown that this fading coloration is likely due to gradual loss with lizard age of an innate capacity for antioxidation due to increasing DNA damage . The majority of lizard species are active during the day , though some are active at night , notably geckos. As ectotherms , lizards have

22780-418: The palms faced the ground or backwards towards the legs. In humans, pronation is achieved by motion of the radius relative to the ulna (the two bones of the forearm). In saurischian dinosaurs, however, the end of the radius near the elbow was actually locked into a groove of the ulna, preventing any movement. Movement at the wrist was also limited in many species, forcing the entire forearm and hand to move as

22950-400: The past considered the herrerasaurians to be members of Theropoda, while other theorized the group to be basal saurischians, and may even have evolved prior to the saurischian-ornithischian split. Cladistic analysis following the discovery of Tawa , another Triassic dinosaur, suggests the herrerasaurs likely were early theropods. The earliest and most primitive unambiguous theropods are

23120-531: The period, where they were geographically separate, the ceratosaurs and allosaurs in Gondwana, and the coelurosaurs in Laurasia. Of all the theropod groups, the coelurosaurs were by far the most diverse. Some coelurosaur groups that flourished during the Cretaceous were the tyrannosaurids (including Tyrannosaurus ), the dromaeosaurids (including Velociraptor and Deinonychus , which are remarkably similar in form to

23290-401: The potential for new medicinal drugs based on lizard venom proteins . Genes associated with venom toxins have been found in the salivary glands of a wide range of lizards, including species traditionally thought of as non-venomous, such as iguanas and bearded dragons. This suggests that these genes evolved in the common ancestor of lizards and snakes , some 200 million years ago (forming

23460-515: The predator's attention from the fleeing prey. Lizards partially regenerate their tails over a period of weeks. Some 326 genes are involved in regenerating lizard tails. The fish-scale gecko Geckolepis megalepis sheds patches of skin and scales if grabbed. Many lizards attempt to escape from danger by running to a place of safety; for example, wall lizards can run up walls and hide in holes or cracks. Horned lizards adopt differing defences for specific predators. They may play dead to deceive

23630-478: The presence of rivals or females. While it is usually males that display, in some species females also use such communication. In the bronze anole , head-bobs are a common form of communication among females, the speed and frequency varying with age and territorial status. Chemical cues or pheromones are also important in communication. Males typically direct signals at rivals, while females direct them at potential mates. Lizards may be able to recognise individuals of

23800-439: The relative absence of trackway evidence for tail dragging suggested that, when walking, the giant, long-tailed theropods would have adopted a more horizontal posture with the tail held parallel to the ground. However, the orientation of the legs in these species while walking remains controversial. Some studies support a traditional vertically oriented femur, at least in the largest long-tailed theropods, while others suggest that

23970-592: The right and left limbs with substantial body bending. This body bending prevents significant respiration during movement, limiting their endurance, in a mechanism called Carrier's constraint . Several species can run bipedally, and a few can prop themselves up on their hindlimbs and tail while stationary. Several small species such as those in the genus Draco can glide: some can attain a distance of 60 metres (200 feet), losing 10 metres (33 feet) in height. Some species, like geckos and chameleons, adhere to vertical surfaces including glass and ceilings. Some species, like

24140-527: The same species by their scent. Acoustic communication is less common in lizards. Hissing , a typical reptilian sound, is mostly produced by larger species as part of a threat display, accompanying gaping jaws. Some groups, particularly geckos, snake-lizards, and some iguanids, can produce more complex sounds and vocal apparatuses have independently evolved in different groups. These sounds are used for courtship, territorial defense and in distress, and include clicks, squeaks, barks and growls. The mating call of

24310-467: The scales. The dentitions of lizards reflect their wide range of diets, including carnivorous, insectivorous, omnivorous, herbivorous, nectivorous, and molluscivorous. Species typically have uniform teeth suited to their diet, but several species have variable teeth, such as cutting teeth in the front of the jaws and crushing teeth in the rear. Most species are pleurodont , though agamids and chameleons are acrodont . The tongue can be extended outside

24480-506: The scientific literature at some point. Von Huene assumed digitigrade bipedality with erect hind limbs for the animals he excavated at Trossingen, with the backbone held at a steep angle (at least during rapid locomotion). In contrast, Jaekel, the main investigator of the Halberstadt material, initially concluded that the animals walked quadrupedally , like lizards, with a sprawling limb position, plantigrade feet, and laterally undulating

24650-468: The scope of Marsh's Order Theropoda, it came to replace a previous taxonomic group that Marsh's rival E. D. Cope had created in 1866 for the carnivorous dinosaurs: Goniopoda ("angled feet"). By the early 20th century, some palaeontologists, such as Friedrich von Huene , no longer considered carnivorous dinosaurs to have formed a natural group. Huene abandoned the name "Theropoda", instead using Harry Seeley 's Order Saurischia , which Huene divided into

24820-601: The secondary meaning "flat" of πλατυς , so that Plateosaurus is often translated as "flat lizard". Often, claims were made that πλατυς is supposed to have been intended as a reference to flat bones, for example the laterally flattened teeth of Plateosaurus , but the teeth and other flat bones such as the pubic bones and some skull elements were unknown at the time of description. Von Meyer's original short description from 1837 did not provide an etymology for Plateosaurus , but noted (as translated into English by British biologist Thomas Henry Huxley in 1870): "The bones belong to

24990-783: The shape of the tooth or denticles . The morphology of the teeth is distinct enough to tell the major families apart, which indicate different diet strategies. An investigation in July 2015 discovered that what appeared to be "cracks" in their teeth were actually folds that helped to prevent tooth breakage by strengthening individual serrations as they attacked their prey. The folds helped the teeth stay in place longer, especially as theropods evolved into larger sizes and had more force in their bite. Mesozoic theropods were also very diverse in terms of skin texture and covering. Feathers or feather-like structures (filaments) are attested in most lineages of theropods (see feathered dinosaur ). However, outside

25160-482: The shells. Larger species, such as monitor lizards, can feed on larger prey including fish, frogs, birds, mammals and other reptiles. Prey may be swallowed whole and torn into smaller pieces. Both bird and reptile eggs may also be consumed as well. Gila monsters and beaded lizards climb trees to reach both the eggs and young of birds. Despite being venomous, these species rely on their strong jaws to kill prey. Mammalian prey typically consists of rodents and leporids ;

25330-536: The skin of lizards is covered in overlapping scales made of keratin . This provides protection from the environment and reduces water loss through evaporation. This adaptation enables lizards to thrive in some of the driest deserts on earth. The skin is tough and leathery, and is shed (sloughed) as the animal grows. Unlike snakes which shed the skin in a single piece, lizards slough their skin in several pieces. The scales may be modified into spines for display or protection, and some species have bone osteoderms underneath

25500-415: The slightest sound. As in snakes and many mammals, all lizards have a specialised olfactory system, the vomeronasal organ , used to detect pheromones . Monitor lizards transfer scent from the tip of their tongue to the organ; the tongue is used only for this information-gathering purpose, and is not involved in manipulating food. Some lizards, particularly iguanas, have retained a photosensory organ on

25670-647: The stem of πλᾰτέος ( plateos ), the genitive case of the masculine adjective platys in Ancient Greek. In the same year, Agassiz proposed that the name derives from the Ancient Greek πλατη ( platê – "paddle", "rudder"; Agassiz translates this as Latin pala = "spade") and σαυρος ( sauros – "lizard"). Agassiz consequently renamed the genus Platysaurus , probably from Greek πλατυς ( platys – "broad, flat, broad-shouldered"), creating an invalid junior synonym. Later authors often referred to this derivation, and

25840-491: The suborders Coelurosauria and Pachypodosauria . Huene placed most of the small theropod groups into Coelurosauria, and the large theropods and prosauropods into Pachypodosauria, which he considered ancestral to the Sauropoda (prosauropods were still thought of as carnivorous at that time, owing to the incorrect association of rauisuchian skulls and teeth with prosauropod bodies, in animals such as Teratosaurus ). Describing

26010-514: The taxonomy (relationships), taphonomy (how the animals became embedded and fossilised), biomechanics (how their skeletons worked), and palaeobiology (life circumstances) of Plateosaurus have been re-studied in detail, altering the interpretation of the animal's biology, posture and behaviour. In 1834, physician Johann Friedrich Engelhardt discovered some vertebrae and leg bones at Heroldsberg near Nuremberg , Germany. Three years later German palaeontologist Hermann von Meyer designated them as

26180-679: The term "breit" [broad] for different features, including "broad, strong limb bones," noting that it had: "mehreren verwachsenen Wirbeln bestehende Heiligenbein, breite, starke Gliedmaassenknochen von 1 1⁄2 Fuss Länge mit einer geräumigen Markhöhle, zierliche Krystalle von Nadeleisenerz einschliessend, so wie Zehenglieder, welche ebenfalls breit und hohl waren...; es wäre diess der älteste bis jetzt aufgefundene Pachypode." [a sacrum composed of several fused vertebrae, broad, strong limb bones 1 1⁄2 feet long with an ample medullary cavity enclosing finely formed crystals of Goethite iron ore, as well as toe phalanges, which were also broad and hollow...; it would be

26350-413: The theropod dinosaurs were the carnivorous Eodromaeus and, possibly, the herrerasaurids of Argentina . The herrerasaurs existed during the early late Triassic (Late Carnian to Early Norian ). They were found in North America and South America and possibly also India and Southern Africa. The herrerasaurs were characterised by a mosaic of primitive and advanced features. Some paleontologists have in

26520-499: The top of their heads called the parietal eye , a basal ("primitive") feature also present in the tuatara . This "eye" has only a rudimentary retina and lens and cannot form images, but is sensitive to changes in light and dark and can detect movement. This helps them detect predators stalking it from above. Until 2006 it was thought that the Gila monster and the Mexican beaded lizard were

26690-615: The type species and possibly not to Plateosaurus at all. Some of this material is not diagnostic; other material has been recognised to be different, but was never sufficiently described. Plateosaurus had the typical body shape of a herbivorous bipedal dinosaur: a small skull, a long and flexible neck composed of 10 cervical vertebrae , a stocky body, and a long, mobile tail composed of at least 40 caudal vertebrae . The arms of Plateosaurus were very short, even compared to most other "prosauropods". However, they were strongly built, with hands adapted for powerful grasping. The shoulder girdle

26860-428: The type species or invalid names. Von Huene practically erected a new species and sometimes a new genus for each relatively complete find from Trossingen (three species of Pachysaurus and seven of Plateosaurus ) and Halberstadt (one species of Gresslyosaurus and eight of Plateosaurus ). Later, he merged several of these species, but remained convinced that more than one genus and more than one species of Plateosaurus

27030-408: The way theropods have often been reconstructed in art and the popular media, the range of motion of theropod forelimbs was severely limited, especially compared with the forelimb dexterity of humans and other primates . Most notably, theropods and other bipedal saurischian dinosaurs (including the bipedal prosauropods ) could not pronate their hands—that is, they could not rotate the forearm so that

27200-603: The wrist not seen in other theropods, thanks to the presence of a specialized half-moon shaped wrist bone (the semi-lunate carpal) that allowed the whole hand to fold backward towards the forearm in the manner of modern birds. In 2001, Ralph E. Molnar published a survey of pathologies in theropod dinosaur bone. He found pathological features in 21  genera from 10 families. Pathologies were found in theropods of all body size although they were less common in fossils of small theropods, although this may be an artifact of preservation. They are very widely represented throughout

27370-623: The young hatch close to 300 days, and the female returns to help them escape the termite mound where the eggs were laid. Around 20 percent of lizard species reproduce via viviparity (live birth). This is particularly common in Anguimorphs. Viviparous species give birth to relatively developed young which look like miniature adults. Embryos are nourished via a placenta -like structure. A minority of lizards have parthenogenesis (reproduction from unfertilised eggs). These species consist of all females who reproduce asexually with no need for males. This

27540-428: Was endothermic . The type species of Plateosaurus is P. trossingensis . Adults of this species reached 4.8 to 10 metres (16 to 33 ft) in length, and ranged in mass from 600 to 4,000 kilograms (1,300 to 8,800 lb). The geologically older species, P. gracilis (formerly named Sellosaurus gracilis ), was somewhat smaller, with a total length of 4 to 5 metres (13 to 16 ft). Plateosaurus

27710-487: Was defined loosely, as large, broad-footed, broad-handed forms with relatively heavy skulls, unlike the smaller " anchisaurids " and sauropod-like " melanorosaurids ". Reevaluation of "prosauropods" in light of the new methods of analysis led to the reduction of Plateosauridae. For many years the clade only included Plateosaurus and various junior synonyms, but later two more genera were considered to belong to it: Sellosaurus and possibly Unaysaurus . Of these, Sellosaurus

27880-460: Was given to Plateosaurus engelhardti , but it was ruled as undiagnostic (i.e. indistinguishable from other dinosaurs) by the ICZN . Currently, there are three valid species; in addition to P. trossingensis , P. longiceps and P. gracilis are also known. However, others have been assigned in the past, and there is no broad consensus on the species taxonomy of plateosaurid dinosaurs. Similarly, there are

28050-408: Was gone by the late Triassic. Digit I is reduced and generally do not touch the ground, and greatly reduced in some lineages. They also lack a digit V on their hands and have developed a furcula which is otherwise known as a wishbone. Early neotheropods like the coelophysoids have a noticeable kink in the upper jaw known as a subnarial gap. Averostrans are some of the most derived theropods and contain

28220-426: Was incapable of pronating its hands. The pronated position in some museum mounts had been achieved by exchanging the position of radius and ulna in the elbow. The lack of forelimb pronation meant that Plateosaurus was an obligate (i.e. unable to walk in any other way) biped. Further indicators for a purely bipedal mode of locomotion are the great difference in limb length (the hind limb is roughly twice as long as

28390-455: Was narrow (often misaligned in skeletal mounts and drawings), with the clavicles (collar bones) touching at the body's midline, as in other basal sauropodomorphs. The hind limbs were held under the body, with slightly flexed knees and ankles, and the foot was digitigrade , meaning the animal walked on its toes. The proportionally long lower leg and metatarsus show that Plateosaurus could run quickly on its hind limbs. The tail of Plateosaurus

28560-646: Was present in both localities. Jaekel also believed that the Halberstadt material included several plateosaurid dinosaurs, as well as non-plateosaurid prosauropods. Systematic research by Galton drastically reduced the number of genera and species. Galton synonymised all cranial material, and described differences between the syntypes of P. engelhardti and the Trossingen material, which he referred to P. longiceps . Galton recognised P. trossingensis ( P. fraasianus and P. integer are junior objective synonyms) to be identical to P. longiceps . Markus Moser, however, showed that P. longiceps

28730-423: Was swimming near the surface of a river and just the tips of its toes and claws could touch the bottom. The tracks indicate a coordinated, left-right, left-right progression, which supports the proposition that theropods were well-coordinated swimmers. During the late Triassic , a number of primitive proto-theropod and theropod dinosaurs existed and evolved alongside each other. The earliest and most primitive of

28900-654: Was typically dinosaurian, muscular and with high mobility. The skull of Plateosaurus is small and narrow, rectangular in side view, and nearly three times as long as it is high. There is an almost rectangular lateral temporal foramen at the back. The large, round orbit (eye socket), the sub-triangular antorbital fenestra and the oval naris (nostril) are of almost equal size. The jaws carried many small, leaf-shaped, socketed teeth: 5 to 6 per premaxilla , 24 to 30 per maxilla , and 21 to 28 per dentary (lower jaw). The thick, leaf-shaped, bluntly serrated tooth crowns were suitable for crushing plant material. The low position of

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