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49-470: Macronaria is a clade of sauropod dinosaurs . Macronarians are named after the large diameter of the nasal opening of their skull, known as the external naris, which exceeded the size of the orbit, the skull opening where the eye is located (hence macro - meaning large, and – naria meaning nose). Fossil evidence suggests that macronarian dinosaurs lived from the Middle Jurassic ( Bathonian ) through

98-526: A Psittacosaurus mongoliensis , from the Ondai Sair Formation , Lower Cretaceous Period of Mongolia , showing a collection of about 40 gastroliths inside the rib cage , about midway between shoulder and pelvis. Gastroliths have sometimes been called Morrison stones because they are often found in the Morrison Formation (named after the town of Morrison , west of Denver , Colorado ),

147-525: A clade (from Ancient Greek κλάδος (kládos)  'branch'), also known as a monophyletic group or natural group , is a grouping of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree . In the taxonomical literature, sometimes the Latin form cladus (plural cladi ) is used rather than the English form. Clades are

196-479: A "ladder", with supposedly more "advanced" organisms at the top. Taxonomists have increasingly worked to make the taxonomic system reflect evolution. When it comes to naming , this principle is not always compatible with the traditional rank-based nomenclature (in which only taxa associated with a rank can be named) because not enough ranks exist to name a long series of nested clades. For these and other reasons, phylogenetic nomenclature has been developed; it

245-412: A calcium source for molting. In 1906, George Reber Weiland reported the presence of worn and polished quartz pebbles associated with the remains of plesiosaurs and sauropod dinosaurs and interpreted these stones as gastroliths. In 1907, Barnum Brown found gravel in close association with the fossil remains of the duck-billed hadrosaur Claosaurus and interpreted it as gastroliths. Brown

294-623: A clade can be described based on two different reference points, crown age and stem age. The crown age of a clade refers to the age of the most recent common ancestor of all of the species in the clade. The stem age of a clade refers to the time that the ancestral lineage of the clade diverged from its sister clade. A clade's stem age is either the same as or older than its crown age. Ages of clades cannot be directly observed. They are inferred, either from stratigraphy of fossils , or from molecular clock estimates. Viruses , and particularly RNA viruses form clades. These are useful in tracking

343-435: A dinosaur's gizzard any genuine gastrolith would have been acted upon by other stones and fibrous materials in a process similar to the action of a rock tumbler . Second, the stone must be unlike the rock found in its geological vicinity, i.e., its geologic context. Many gastroliths have been found in fine grained lake, mud, and swamp deposits. These environs are calm water deposits and could not carry pebbles and cobbles (unlike

392-472: A fossil location in northwestern Wyoming also yielded dinosaur bones with their associated gastroliths. In 1942, William Lee Stokes recognized the presence of gastroliths in the remains of sauropod dinosaurs recovered from Late Jurassic strata . Geologists usually require several pieces of evidence before they will accept that a rock was used by a dinosaur to aid its digestion . First, it should be rounded on all edges (and some are polished) because inside

441-627: A late Jurassic formation roughly 150 million years old. Some gastroliths are made of petrified wood . Most known instances of preserved sauropod gastroliths are from Jurassic animals. The Early Cretaceous Cedar Mountain Formation of Central Utah is full of highly polished red and black cherts , and other rounded quartzose clasts, which may partly represent gastroliths. The cherts may themselves contain fossils of ancient animals, such as corals. These stones do not appear to be associated with stream deposits and are rarely more than fist-sized, which

490-511: A length of 10 centimetres (3.9 in) . Apparent microgastroliths have also been found in frog tadpoles. Ingestion of silt and gravel by tadpoles of various anuran (frog) species has been observed to improve buoyancy control. Some extinct animals such as sauropod dinosaurs appear to have used stones to grind tough plant matter. A rare example of this is the Early Cretaceous theropod Caudipteryx zoui from northeastern China, which

539-422: A revised taxonomy based on a concept strongly resembling clades, although the term clade itself would not be coined until 1957 by his grandson, Julian Huxley . German biologist Emil Hans Willi Hennig (1913–1976) is considered to be the founder of cladistics . He proposed a classification system that represented repeated branchings of the family tree, as opposed to the previous systems, which put organisms on

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588-517: A river or beach). Oliver Wings also argues that the stone must be found with the fossils of the dinosaur which ingested it. It is this last criterion that causes trouble in identification, as smooth stones found without context can (possibly erroneously in some cases) be dismissed as having been polished by water or wind. Christopher H. Whittle (1988,9) pioneered scanning electron microscope analysis of wear patterns on gastroliths. Wings (2003) found that ostrich gastroliths would be deposited outside

637-565: A soapy texture to identify gastroliths as "unreliable". Gastroliths tended to be universally dull, although the colors represented were varied including black, dark brown, purplish red and grey-blue. Reflectance values greater than 50% are very diagnostic for identifying gastroliths. Clasts from beaches and streams tended to have reflectance values of less than 35%. Less than ten percent of beach clasts have reflectance values lying between 50 and 80%. The American Museum of Natural History Photograph # 311488 demonstrates an articulated skeleton of

686-413: A steady size decrease over time. Sauropods, widely speaking, have been associated with both coastal and inland environments. It is believed that macronarians such as titanosaurs were strictly terrestrial and associated with inland environments such as lacustrine systems. These findings are based on ‘wide-gauged’ trackways produced by titanosaurs which are strongly correlated with terrestrial sediments. It

735-429: A suffix added should be e.g. "dracohortian". A clade is by definition monophyletic , meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. The ancestor can be known or unknown; any and all members of a clade can be extant or extinct. The science that tries to reconstruct phylogenetic trees and thus discover clades is called phylogenetics or cladistics ,

784-430: Is almost non-existent. Given the large body size of these neosauropod herbivores, it is thought that this type of niche partitioning, characterized by different species taking advantage of different resources, was necessary for coexistence. It was at one point believed that polished pebbles occasionally found with sauropod skeletons were gastroliths . Gastroliths are stones intentionally swallowed to aid with digestion (as

833-676: Is also believed that macronarians have Gondwanan origins. A possible camarasauromorph of indeterminate genus and species was reported from the Middle Jurassic Khadir Formation of India , representing the oldest member of camarasauromorpha . Camarasaurus is among the most commonly found dinosaur from the Late Jurassic deposits of the Morrison Formation in the US. Unlike Camarasaurus, Titanosaurs were most commonly found in

882-499: Is also used with a similar meaning in other fields besides biology, such as historical linguistics ; see Cladistics § In disciplines other than biology . The term "clade" was coined in 1957 by the biologist Julian Huxley to refer to the result of cladogenesis , the evolutionary splitting of a parent species into two distinct species, a concept Huxley borrowed from Bernhard Rensch . Many commonly named groups – rodents and insects , for example – are clades because, in each case,

931-595: Is composed of several subclades and families notably including Camarasauridae and Titanosauriformes , among several others. Titanosauriforms are particularly well known for being some of the largest terrestrial animals to ever exist. Macronaria was described by Wilson and Sereno who proposed the new subdivisions among the clade Neosauropoda . Previously, this clade was thought to have Brachiosaurus and Camarasauridae forming one sister group, and Titanosauroidea and Diplodocoidea forming another. This proposed shift with Macronaria placed Diplodocoidea as an outgroup to

980-472: Is consistent with the idea that they are gastroliths. Most known instances of preserved sauropod gastroliths are from Jurassic animals. The largest known gastroliths found in association with sauropod skeletons are approximately ten centimeters in length. In 2001 Frank Sanders , Kim Manley , and Kenneth Carpenter published a study on 115 gastroliths discovered in association with a Cedarosaurus specimen. The stones were identified as gastroliths on

1029-471: Is in turn included in the mammal, vertebrate and animal clades. The idea of a clade did not exist in pre- Darwinian Linnaean taxonomy , which was based by necessity only on internal or external morphological similarities between organisms. Many of the better known animal groups in Linnaeus's original Systema Naturae (mostly vertebrate groups) do represent clades. The phenomenon of convergent evolution

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1078-524: Is nested within Neosauropoda and is sister to Diplodocoidea. These groups split around the mid- to late-Jurassic and end at the K/Pg boundary . In the less than 100 Myr that they lived, macronarians developed at least 216 synapomorphies and autapomorphies . Despite the fact that macronarians are named after cranial openings, they are described by more appendicular synapomorphies. The species that survived late into

1127-515: Is responsible for many cases of misleading similarities in the morphology of groups that evolved from different lineages. With the increasing realization in the first half of the 19th century that species had changed and split through the ages, classification increasingly came to be seen as branches on the evolutionary tree of life . The publication of Darwin's theory of evolution in 1859 gave this view increasing weight. In 1876 Thomas Henry Huxley , an early advocate of evolutionary theory, proposed

1176-470: Is seen in a variety of modern birds). However, more recent taphonomic and sedimentological evidence suggests that sauropods did not use stones for digestion due to the general rarity of finding gastric mill-like stones with sauropod remains, and low relative mass of the stones to the size of sauropod bodies. When gastrolith-like rocks are found with sauropods, it may be that they were accidentally ingested, or intentionally ingested for mineral uptake. Macronaria

1225-489: Is still controversial. As an example, see the full current classification of Anas platyrhynchos (the mallard duck) with 40 clades from Eukaryota down by following this Wikispecies link and clicking on "Expand". The name of a clade is conventionally a plural, where the singular refers to each member individually. A unique exception is the reptile clade Dracohors , which was made by haplology from Latin "draco" and "cohors", i.e. "the dragon cohort "; its form with

1274-548: Is thought to have had a maximum of three replacement teeth and tooth formation took about 315 days. The replacement rate is thought to be one tooth every 62 days – this is about the same level or higher than non-sauropod herbivores, though it is lower than the replacement rates of the sister taxa, Diplodocus. It is thought that this may be related to the fact that the low-browsing taxa ingested more grit and thus needed to replace teeth more, while Camarasaurus and other macronarians fed on mid to upper canopy plants where exogenous grit

1323-522: Is unlikely that they were ingested by accident. Cedarosaurus may have found irregular clasts to be attractive potential gastroliths or was not selective about shape. The clasts were generally of dull coloration, suggesting that color was not a major factor for the sauropod's decision making. The high surface area to volume ratio of the largest clasts suggests that the gastroliths may have broken down ingested plant material by grinding or crushing it. The sandstone clasts tended to be fragile and some broke in

1372-409: The short-necked plesiosaurs . While some fossil gastroliths are rounded and polished, many stones in living birds are not polished at all. Gastroliths associated with dinosaur fossils can weigh several kilograms. Certain crayfish store gastroliths in their stomachs. Crayfish living in freshwater store these gastroliths as the presence of calcium is limited in freshwater. These gastroliths serve as

1421-1555: The Cretaceous were characterized by stocky, wide-gauged posture, most notably the highly derived saltasaurines . Also under Macronaria are Camarasaurus , Brachiosaurus , and Titanosauria . Camarasauromorpha is the most basal group of Macronaria. The cladogram below follows José Luis Barco Rodríguez (2010). Camarasauridae Galvesaurus Phuwiangosaurus Aragosaurus Tastavinsaurus [REDACTED] Venenosaurus Brachiosaurus [REDACTED] Euhelopus [REDACTED] Titanosauria [REDACTED] The cladogram below follows José L. Carballido, Oliver W. M. Rauhut, Diego Pol and Leonardo Salgado (2011). Camarasaurus Europasaurus Galvesaurus Tehuelchesaurus [REDACTED] Janenschia Tastavinsaurus [REDACTED] Euhelopus [REDACTED] Chubutisaurus Wintonotitan [REDACTED] Brachiosauridae [REDACTED] Phuwiangosaurus Titanosauria [REDACTED] Simplified cladogram of Macronaria after D'Emic (2012). Camarasauridae Tehuelchesaurus [REDACTED] Brachiosauridae [REDACTED] Euhelopodidae [REDACTED] Chubutisaurus Titanosauria [REDACTED] For alternative cladograms see also Mateus et al. (2011), Mannion et al. (2013). [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Clade In biological phylogenetics ,

1470-645: The Late Cretaceous ( Maastrichtian ). Macronarians have been found globally, including discoveries in Argentina, the United States, Portugal, China, and Tanzania. Like other sauropods , they are known to have inhabited primarily terrestrial areas, and little evidence exists to suggest that they spent much time in coastal environments. Macronarians are diagnosed through their distinct characters on their skulls, as well as appendicular and vertebral characters. Macronaria

1519-543: The Southern Hemisphere with the exception of Alamosaurus which was found in North America. There is strong geologic evidence that a land bridge between South and North America existed at the end of the Cretaceous allowing for dispersal of organisms between the two landmasses. Cretaceous sauropods are thought to have moved northward from South America, thus explaining the high density of South American sauropods, and

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1568-449: The animal died and many entered a stream or beach environment, some gastroliths show a mixture of these wear features. Others were undoubtedly swallowed by other dinosaurs and highly polished gastroliths may have been swallowed repeatedly. None of the gastroliths examined in a 2001 study of Cedarosaurus gastroliths had the "soapy" texture popularly used to distinguish gastroliths from other types of clast. The researchers dismissed using

1617-469: The basis of their tight spatial distribution, partial matrix support, and an edge-on orientation indicative of their being deposited while the carcass still had soft tissue. Their high surface reflectance values are consistent with other known dinosaur gastroliths. Nearly all of the Cedarosaurus gastroliths were found within a .06 m volume of space in the gut region of the skeleton. The total mass of

1666-458: The evolution of body size with some members both increasing and decreasing in size from the primitive condition. For example, despite all being in the titanosaur clade, Argentinosaurus reached enormous sizes (~50 tons), while Saltasaurus and Magyarosaurus reached only 1.5-3 metric tons, which is fairly small for sauropods. While some macronarians represent some of the largest terrestrial vertebrates ever known, other macronarians experienced

1715-451: The fundamental unit of cladistics , a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population , or a species ( extinct or extant ). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed monophyletic (Greek: "one clan") groups. Over

1764-421: The gastroliths themselves was 7 kilograms (15 lb). Most were less than 10 millilitres (0.35 imp fl oz; 0.34 US fl oz) in volume. The least massive clast was 0.1 grams (0.0035 oz) and the most was 715 grams (25.2 oz), with most of them being toward the smaller end of that range. The clasts tended to be close to spherical in shape, although the largest specimens were also

1813-546: The group consists of a common ancestor with all its descendant branches. Rodents, for example, are a branch of mammals that split off after the end of the period when the clade Dinosauria stopped being the dominant terrestrial vertebrates 66 million years ago. The original population and all its descendants are a clade. The rodent clade corresponds to the order Rodentia, and insects to the class Insecta. These clades include smaller clades, such as chipmunk or ant , each of which consists of even smaller clades. The clade "rodent"

1862-473: The higher surfaces, with little or no polish in depressions or crevices, often strongly resembling the surface of worn animal teeth. Stream- or beach-worn rocks, particularly in a high-impact environment, show less polishing on higher surfaces, often with many small pits or cracks on these higher surfaces. Finally, highly polished gastroliths often show long microscopic rilles, presumably caused by contact with stomach acid. Since most gastroliths were scattered when

1911-448: The important information they can provide, if indeed they are trace fossils. If the validity of such gastroliths can be verified, it may be possible to trace gastrolithic rocks back to their original source area where the dinosaur first swallowed the rock. This may provide important information on how dinosaurs migrated. Because the number of suspected gastroliths is substantial, they might provide significant new information and insights into

1960-590: The last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming taxa that are not clades; that is, taxa that are not monophyletic . Some of the relationships between organisms that the molecular biology arm of cladistics has revealed include that fungi are closer relatives to animals than they are to plants, archaea are now considered different from bacteria , and multicellular organisms may have evolved from archaea. The term "clade"

2009-518: The latter term coined by Ernst Mayr (1965), derived from "clade". The results of phylogenetic/cladistic analyses are tree-shaped diagrams called cladograms ; they, and all their branches, are phylogenetic hypotheses. Three methods of defining clades are featured in phylogenetic nomenclature : node-, stem-, and apomorphy-based (see Phylogenetic nomenclature§Phylogenetic definitions of clade names for detailed definitions). The relationship between clades can be described in several ways: The age of

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2058-401: The most irregular. The largest gastroliths contributed the most to the total surface area of the set. Some gastroliths were so large and irregularly shaped that they may have been difficult to swallow. The gastroliths were mostly composed of chert , with some sandstone , siltstone , and quartzite clasts also included. Since some of the most irregular gastroliths are also the largest, it

2107-447: The new clade Macronaria, under which all other neosauropods would fall. The following list includes some of the distinguishing characteristics that are diagnostic for Macronaria: The posture of macronarians is characterized by a novel ‘wide-gauged’ locomotor style, particularly in titanosaurs . While sauropods are known to be the giants of the dinosaurs, macronarians were not exclusively large-bodied. Macronarians show divergence in

2156-525: The process of collection. The sandstone gastroliths may have been rendered fragile after deposition by loss of cement caused by the external chemical environment. If the clasts had been that fragile while the animal was alive, they probably rolled and tumbled in the digestive tract. If they were more robust, they could have served as part of a ball-mill system. Paleontologists and geologists are researching new methods of identifying gastroliths that have been found disassociated from animal remains, because of

2205-498: The skeleton if the carcass was deposited in an aquatic environment for as little as a few days following death. He concludes that this is likely to hold true for all birds (with the possible exception of moa ) due to their air-filled bones which would cause a carcass deposited in water to float for the time it needs to rot sufficiently to allow gastroliths to escape. Gastroliths can be distinguished from stream- or beach-rounded rocks by several criteria: gastroliths are highly polished on

2254-513: The sole appearance of Alamosaurus in the Western Interior. It is well established that all sauropods, including macronarians, were obligate herbivores. Unlike their sister group, the diplodocids, which were thought to feed on low-lying plants, camarasaurids and other macronarians likely had strongly upward-oriented necks for browsing trees and taller plants. Each tooth family in Camarasaurus

2303-757: The spread of viral infections . HIV , for example, has clades called subtypes, which vary in geographical prevalence. HIV subtype (clade) B, for example is predominant in Europe, the Americas and Japan, whereas subtype A is more common in east Africa. Gastroliths Gastrolith comes from the Greek γαστήρ ( gastēr ), meaning "stomach", and λίθος ( lithos ), meaning "stone". Among living vertebrates , gastroliths are common among crocodiles , alligators , herbivorous birds , seals and sea lions . Domestic fowl require access to grit . Stones swallowed by ostriches can exceed

2352-519: Was among the first paleontologists to recognize that dinosaurs used gastroliths in their digestive systems to aid in the grinding of food. Other paleontologists over the years were unconvinced. In 1932, Friedrich von Huene found stones in Late Triassic sediments, in association with the fossil remains of the prosauropod Sellosaurus and interpreted them as gastroliths. In 1934, the Howe Quarry,

2401-410: Was discovered with a series of small stones, interpreted as gastroliths, in the area of its skeleton that would have corresponded with its abdominal region. Aquatic animals, such as plesiosaurs , may have used them as ballast, to help balance themselves or to decrease their buoyancy, as crocodiles do. Research indicates that the presence of gastroliths in elasmosaurid plesiosaurs differs from that of

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