A haemal arch , also known as a chevron , is a bony arch on the ventral side of a tail vertebra of a vertebrate . The canal formed by the space between the arch and the vertebral body is the haemal canal . A spinous ventral process emerging from the haemal arch is referred to as the haemal spine .
41-526: Bagualia (meaning "wild horse"), is an extinct genus of eusauropod dinosaur , from the Early Jurassic (Middle Toarcian ) Epoch in what is now the Chubut Province of Argentina. The type species , B. alba , was formally described in 2020. Bagualia represents the oldest definitive Eusauropod, and due to the completeness of its material it represents one of the most important taxa for understanding
82-547: A distally elongated anterior ramus of the quadratojugal. Separating the anteroventral process of the nasal from the posterolateral process of the premaxilla, eusauropods also have a long maxilla that forms the posteroventral margin of the external naris. Eusauporoda are also hypothesized to have a semi-digitigrade foot posturem demonstrated by footprint evidence. Paleontologist Jeffrey Wilson explains that eusauropods differ from theropods and prosauropods that have digitigrade pes where their heel and metatarsals are lifted off
123-525: A lacustrine environment beneath a basaltic layer. The fossils include the holotype , MPEF-PV 3301 (a partial skull with cervical vertebrae), and additional remains from at least three individuals (MPEF-PV 3305–3348). The generic name , Bagualia comes from "bagual," the Spanish word for "wild horse," referencing the specimens' discovery in the Bagual Canyon (" Cañadón Bagual "). The specific name , alba ,
164-418: A medial convex area and a procumbent arrangement typical of eusauropods. Numerous small pores on the ventral margin, along with little wear on the first erupted tooth, may indicate a vascular function, possibly supporting a keratin-like covering. All cervical vertebrae exhibit an opisthocoelous structure, featuring elongated centra and a ventral keel. The recovered proatlas is robust and rhomboid in shape, while
205-403: A retracted position of the external nares. Unlike prosauropods and theropods , which have a snout with smooth, unprotruding alveolar and subnarial regions, eusauropods have snouts with “stepped anterior margins”. Further distinguishing features of eusauropods include the absence of the contact between the squamosal and the quadratojugal, the absence of the anterior process of the prefrontal, and
246-422: A smooth lateral surface with several foramina, and its anterior margin lacks a step. A beak -like process is present at the anteroventral end, unique to Bagualia , which may have supported a larger keratinous structure. The maxilla of Bagualia shows 13 alveoli, with some teeth preserved in varying stages of eruption. It has a prominent premaxillary process and a deep narial fossa. Although the ascending process of
287-433: A “bulk-browsing mode of feeding”. They describe the development of lateral plates on the alveolar margins of tooth-bearing bones. These plates can be used to strip foliage, the eusauropod's “U-shaped” jaws create a wide bite, and their loss of “fleshy cheeks” increased the gape. The crowns of eusauropod teeth also have “wrinkled enamel textures”, but it is unclear what this meant for their feeding habits. The skull length of
328-409: Is a Spanish word meaning "dawn," highlighting the dinosaur's early age in the sauropod lineage. Bagualia is known from many bones from three individuals, including vertebrae from the neck, back, and tail, limb and girdle bones, as well as skull and teeth fragments. The size of Bagualia was likely brought on by a newly formed ecosystem and climate shifts, which were all caused by volcanic activity in
369-431: Is a derived clade of sauropod dinosaurs . Eusauropods represent the node-based group that includes all descendant sauropods starting with the basal eusauropods of Shunosaurus , and possibly Barapasaurus , and Amygdalodon , but excluding Vulcanodon and Rhoetosaurus . The Eusauropoda was coined in 1995 by Paul Upchurch to create a monophyletic new taxonomic group that would include all sauropods, except for
410-645: Is considered to be an early member of Eusauropoda . Due to its provenance from the Cañadon Asfalto Formation , which is dated to the Toarcian , its describers interpret this as evidence of a eusauropod dominance after an Early Jurassic global warming event, replacing more basal sauropodomorphs. Successive phylogenetic analyses from 2020, 2021, and 2024 have confirmed a close relationship between Bagualia , Nebulasaurus , Patagosaurus , and Spinophorosaurus . The results of Gomez et al. (2024) are shown in
451-493: Is nearly complete and ossified, showcasing a robust and tall structure similar to other eusauropods. It features limited cranial pneumaticity and lacks certain recesses, with an elliptical foramen magnum dorsoventrally oriented, contrasting with the circular shape seen in many non-sauropod sauropodomorphs. The paroccipital process is laterally projected, with a unique morphology that differs from other sauropodomorphs. The right dentary has 16 alveoli and shows an emerging tooth, while
SECTION 10
#1732873471805492-583: The Bagualia fossils, the site also yielded remains of different conifer families, turtle fossils, and teeth from at least four theropod dinosaurs. The presence of these diverse remains, mixed in the sediment, suggests a rich and complex ecosystem during the Early Jurassic period. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Eusauropoda Eusauropoda (meaning "True Lizard Foot")
533-588: The Cañadón Asfalto Formation hosted a hypersaline and alkaline lake similar to modern Lake Magadi in Kenya, while nearby environments were developed in a similar way to modern Waimangu Volcanic Rift Valley of New Zealand, with the nearby volcanic influence of the Chon Aike Province that likely developed in a similar way to modern California volcanic fields. The holotype of Asfaltovenator comes from
574-581: The Northern Hemisphere , and titanosaurs being found in Southern Hemisphere . However, basal eusauropods that do not fall into either group are fairly well represented. Early eusauropods such as Volkeimeria and Amygdalodon , and more derived eusauropods such as Patagosaurus have been found in South America . Volkeimeria is classified as a basal eusauropod, though in 2004 Paul Upchurch
615-410: The Southern Hemisphere during the Early Jurassic . While the harsh climate and ashes drove most sauropodomorphs to extinction, Bagualia was able to adapt to newly sprouted conifers and plants , using its long neck to snip plant matter from them while staying in place, conserving energy. Its teeth are surrounded by a thick layer of enamel, roughly 7x thicker than other extinct herbivores, enabling
656-546: The Toarcian Oceanic Anoxic Event , what may have been a key for their success after local environmental change. This adaptation allowed it to process fibrous plant material, reflecting its capacity to exploit new dietary resources during the end of the Early Jurassic. The features of Bagualia highlight a key evolutionary step between early sauropodomorphs and derived eusauropods, suggesting significant ecological interactions as environments changed. In addition to
697-514: The cladogram below: Antetonitrus Ingentia Lessemsaurus Ledumahadi Pulanesaura Gongxianosaurus Amygdalodon NHMUK PVR 36834 Archaeodontosaurus Volkheimeria Sanpasaurus Vulcanodon Tazoudasaurus Shunosaurus Barapasaurus Patagosaurus Bagualia Nebulasaurus Spinophorosaurus Tonganosaurus Mamenchisauridae Cetiosaurus Turiasauria Jobaria Neosauropoda The Chacritas Member of
738-487: The "Chacritas Paleolake", and seems to have been a rather saline or even hypersaline hydrologically closed pan lake, shallow in depth, with marginal zones and palustrine subenvironments made of low-energy ramp-like margins. Bagualia has important paleoecological implications due to its robust skull and broad teeth, which indicate a shift towards bulk browsing on tough vegetation, such as conifers from families like Araucariaceae , Cheirolepidiaceae , and Cupressaceae after
779-1174: The Canadon Asfalto and Canadon Calcereo formations reveal a more diverse and widespread peleobiology of eusauropods in the Late Jurassic period. The following cladogram demonstrates hypothesized relationships within the Eusauropoda. The basal eusauropods include the Turiasauria ( Turiasaurus , Zby and others). Shunosaurus Barapasaurus Patagosaurus Omeisaurus Mamenchisaurus Cetiosaurus Jobaria Haplocanthosaurus Limaysaurus Nigersaurus Amargasaurus Dicraeosaurus Apatosaurus Brontosaurus Barosaurus Diplodocus Camarasaurus Brachiosaurus Phuwiangosaurus Malawisaurus Rapetosaurus Isisaurus Opisthocoelicaudia Saltasaurus [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Haemal arch Blood vessels to and from
820-608: The Chacritas Member of the Cañadón Asfalto Formation. This member is mostly made up of two major depositional settings: lacustrine and fluvial deposits. Both of these have intervals of tuffaceous materials, suggesting the presence of volcanic activity. Palustrine littoral environment levels are seen at Cerro Cóndor and Estancia Fossati, characterized by the presence of lacustrine limestones interbedded with shales, tuffs and sandstones. The lacustrine section has been called
861-427: The animal to better shear conifer leaves. The digestive system of Bagualia was also a likely reason why it grew to such a large size, and another function of its long neck has been proposed: it may have dissipated heat in a similar fashion to how elephants use their ears. The skull of Bagualia is relatively complete. The premaxilla is robust and nearly complete with a tall, lateromedially compressed structure, with
SECTION 20
#1732873471805902-485: The atlas is distinguished by its elongated neurapophyses. The axis reveals notable features, such as deep lateral fossae and a prominent neural arch, indicating the holotype likely belonged to a subadult individual. Cervical ribs feature a tetraradiate shape at their proximal ends, characterized by a prominent tuberculum, capitulum, and anterior process, along with a long, slender shaft directed posteriorly, consistent with most sauropods. The preserved dorsal vertebrae, unlike
943-432: The basal eusauropod, Patagosaurus is about 60 centimetres (24 in). One of the most basal eusauropods, Shunosaurus , has two characteristic features of the eusauropod elongated neck: the incorporation of the equivalent of the first dorsal vertebra into the cervical region of the spine, and the addition of two cervical vertebra in the middle of the cervical vertebrae. Other synapomorphies of Eusauropoda includes
984-479: The cervical vertebrae, exhibit more developed zygapophyses, apophyses, and bony laminae. The parapophyses shift from the mid-length of the centrum in the anterior dorsal vertebrae to the neural arch starting from the third dorsal vertebra, a characteristic found in all sauropods. The dorsal ribs are represented by various isolated fragments that cannot be accurately matched. The pelvic girdle is compressed and misaligned, with left elements shifted posteriorly relative to
1025-404: The distinctive shape of its haemal arches, which were forked to have both an anterior and posterior process. Though once thought to be a specialized characteristic of Diplodocus and its close relatives, forked chevrons are now known to have been widespread among sauropod dinosaurs, although titanosauriform sauropods returned to the unforked condition. This vertebrate anatomy –related article
1066-512: The distribution of some of these shared derived traits that distinguish Eusauropoda is still completely clear. However the discovery of the vulcanodont, Tazoudasaurus , which does preserve cranial material did help refine some of the characteristics. Eusauropods are long-necked, strictly herbivorous , obligate quadrupedals . They have a highly specialized set of skeletal adaptions due to their large size, and are graviportal . Yates and Upchurch described eusauropod evolution as moving towards
1107-640: The early evolution of the group. The Bagualia fossil material was discovered in Bagual Canyon, approximately 4.3 kilometres (2.7 mi) from Cerro Cóndor in Chubut, Argentina within the Early Jurassic deposits of the Cañadón Asfalto Formation . The fossils were excavated by the Museo Paleontológico Egidio Feruglio during fieldwork in 2007 and 2009. The remains were embedded in a dark grey pelitic matrix rich in organic matter. This layer, dated precisely to around 179 million years ago, formed in
1148-487: The elongation index, neural spine inclination, and transverse process development. The anterior caudal vertebrae display distinct morphology with amphicoelous centra and well-developed transverse processes, while the middle vertebrae are more elongated with marked articular facets for haemal arches . In the posterior caudal vertebrae, the centra are significantly longer than tall, lacking transverse processes and lateral fossae, with decreasing neural spine angles observed towards
1189-515: The genus Shunosaurus is likely one of the most basal eusauropods. The genus Barapasaurus has been found in India, and may represent a cetiosaurid, a basal eusauropod, or a genus outside Eusauropoda. The data around sauropods evolution, as Novas points out, is largely based on a few formations mostly in the Northern Hemisphere. However, other beds in places such as Tanzania, specifically
1230-629: The ground. Eusauropods show asymmetry in their metatarsal shaft diameters where metatarsal I is broader than the others, suggesting that their weight was mostly assumed by their inner feet. According to Steven Salisbury and Jay Nair, basal eusauropods retain four pedal unguals but reduce their phalangeal number in their fourth digit to three units. The metatarsus in eusauropods is less than a quarter of their tibial length, unlike sauropod outgroups that have long hindlimbs and metatarsus that are almost half of their tibial length. Eusauropods are found on all major continents, with diplocodoids being widespread in
1271-400: The lacrimal, nasal, and frontal bones, characterized by its elongated shape and triangular cross-section. The postorbital forms the posterior and posterodorsal boundaries of the orbit, featuring a slender ventral process typical of early sauropodomorphs. The robust squamosals have four articulating processes, with the longest ventral process contributing to an 'S'-shaped profile. The braincase
Bagualia - Misplaced Pages Continue
1312-451: The left dentary has 14 alveoli with five partially erupted teeth. Notably, these dentaries exhibit a U-shaped configuration characteristic of eusauropods, featuring unique structural traits, including well-developed alveoli and a prominent coronoid process on the surangular. The teeth are spoon-shaped with heavily wrinkled enamel, displaying asymmetrical mesial and distal margins, characteristic of many sauropodomorphs, with notable features like
1353-568: The maxilla is missing, the antorbital fenestra and lacrimal processes are well-defined. The maxilla articulates with the jugal and palatine, but lacks contact with the ectopterygoid. The right nasal has a broad but damaged articulation with the frontal and a thinner connection with the prefrontal. The lacrimal is robust and dorsoventrally tall, with distinct articulations for the jugal, maxilla, prefrontal, and nasal, similar to other sauropods like Camarasaurus and Turiasaurus . The rhomboid-shaped left prefrontal features prominent articular facets for
1394-576: The possibly eusauropod genera Cardiodon and Oplosaurus , known only from teeth. The family Mamenchisauridae is found widespread throughout Asia. A majority of the genera are found in China, although a possible specimen of Mamenchisaurus has been found in Thailand . Also in China, the basal eusauropod Nebulasaurus taito was found to be a sister taxon to Spinophorosaurus , and more derived than Mamenchisauridae, but less derived than Patagosaurus , and
1435-448: The right. The sacrum, composed of five vertebrae, has fused sacral ribs, with variations in development and orientation. The neural spines are plate-like and lack lateral fossae, differing from those of some other sauropods, and are fused and posteriorly curved. The sacral ribs are positioned away from the acetabulum, indicating a non-sauropod sauropodomorph structure. The caudal vertebrae demonstrate distinguishing characteristics including
1476-417: The tail run through the arch. In reptiles, the caudofemoralis longus muscle, one of the main muscles involved in locomotion, attaches to the lateral sides of the haemal arches. In 1956, Alfred Sherwood Romer hypothesized that the position of the first haemal arch was sexually dimorphic in crocodilians and dinosaurs. However, subsequent research established that the size and position of the first haemal arch
1517-422: The tail's end. The haemal arches contain a canal that occupies roughly 20% of the overall chevron length, exhibiting differences when analyzed alongside other eusauropod lineages. Their concave surfaces, extended ventral blades, and central ridges align with characteristics observed in multiple sauropod taxa. Additionally, the posterior haemal arches tend to become shorter and thicker at their distal ends. Bagualia
1558-576: The vulcanodontids. Eusauropoda are herbivorous, quadrupedal, and have long necks. They have been found in South America, Europe, North America, Asia, Australia, and Africa. The temporal range of Eusauropoda ranges from the early Jurassic to the Latest Cretaceous periods. The most basal forms of eusauropods are not well known and because the cranial material for the Vulcanodon is not available, and
1599-709: Was found in Morocco , and Jobaria was found in Niger. However, both genera have been found as possible Macronarians, but Atlasaurus was found to be a turiasaurian, and Jobaria a eusauropod, by a phylogenetic analysis of Xing in 2012. In Europe, the clade Turiasauria has been found in France, Spain, and possibly England, with multiple genera from the same locality in Spain. Cetiosaurus skeletons have also been found in England, along with
1640-426: Was not sexually dimorphic in crocodilians and found no evidence of significant variation in tyrannosaurid dinosaurs, indicating that haemal arches could not be used to distinguish between sexes after all. Haemal arches play an important role in the taxonomy of sauropod dinosaurs , as sauropods exhibit a wide range of morphologies of the haemal arches. In 1878, Othniel Marsh named the sauropod Diplodocus after
1681-403: Was suspicious of its placement, because of its “opisthoceolous cervical centra, the absence of a femoral anterior trochanter, and laterally projecting cnemial crest of the tibia”, and instead thought it may be a generic sauropod. African eusauropods may include Spinophorosaurus , from Niger, although that taxon may instead be closer to Vulcanodon and outside Eusauropoda. Also, Atlasaurus