Patagosaurus (meaning "Patagonia lizard") is an extinct genus of eusauropodan dinosaur from the Middle Jurassic of Patagonia, Argentina. It was first found in deposits of the Cañadón Asfalto Formation, which date to around 165 to 161 million years ago. Although originally twelve specimens were assigned to the taxon, at least one of them may belong to a different genus. Patagosaurus probably lived alongside genera as Piatnitzkysaurus, Condorraptor, and Volkheimeria.
Since Patagosaurus is known from many specimens, including at least one juvenile, its anatomy and growth are fairly well understood. Both ages exhibit the typical features of a sauropod, a long neck, small head, a long tail, and being quadrupedal. The juvenile exhibits features different from the adult in regions like the mandible, pectoral girdle, pelvis and hindlimb, although overall their anatomy is quite similar. The many known specimens help fill in gaps in the anatomy of the genus, such as the forelimb and skull. Parts of the skeleton, like the pectoral girdle, tibia, and pubis are more robust, while others, like the forelimb and ischium, are more gracile. The material of Patagosaurus is similar to closely related taxa like Cetiosaurus and Volkheimeria, more primitive genera such as Barapasaurus and Amygdalodon, and more derived sauropods like Diplodocus and Camarasaurus.
|Restored skeleton with reconstructed skull, Museo Argentino de Ciencias Naturales|
In the 1970s many specimens of a previously unidentified dinosaur were found associated together in the same bed and locality: a pebbly stratum near a route to Cerro Condor. The specimens were first described by Jose Bonaparte in 1979. For the fossil he erected the genus Patagosaurus, as well as its type species P. fariasi. The generic name of Patagosaurus comes from the location of its find in Patagonia, and the fact that it is a reptile. The specific name honours Ricardo Farias, on whose land the initial discovery was made. The genus was originally known from an almost complete postcranial skeleton lacking a skull as the holotype, and many referred specimens however in 2003 it was found that a dentary was referable to the species, so more specimens are probably this taxon. Its skeleton was found near those of Piatnitzkysaurus and Volkheimeria in the Callovian to Oxfordian aged Patagonian deposits of the Cañadón Asfalto Formation. Patagosaurus is almost completely known with many articulated specimens found covering almost all of the skeleton, including parts of the skull. Over twelve specimens have been referred to the species, although some of the material is probably from a unique taxon. Bonaparte (1986) assigned three specimens other than the holotype PVL 4170, PVL 4076, MACN CH 934, and MACN CH 933 to the genus. While the holotype includes a postcranial skeleton, the others are known from cranial material and a nearly complete juvenile skeleton and skull. MACN CH 933 is directly comparable with the type material of Patagosaurus, which confirms its association with the genus. A specimen first referred to Patagosaurus in 2003, MPEF-PV 1670 (which includes just a lower jaw), is also very similar to MACN CH 933, and differences can be associated with age, so therefore, MPEF-PV 1670 presumably represents adult cranial material. However, the teeth of MACN CH 934 are very different from those of both lower jaws (MACN CH 933 and MPEF-PV 1670), so it can be identified as another sauropod from the same deposit as Patagosaurus. Thus, the taxon only certainly includes PVL 4170, MACN CH 933, and MPEF-PV 1670.
Patagosaurus is a sauropod that possessed a general and unspecialized bauplan of being quadrupedal, having an elongate neck, a small head, and a very long tail. Therefore, it is similar to Cetiosaurus and other related genera, who possessed the same morphology. It has been estimated that it was about 16.5 m (54 ft) long and weighed about 7.88 t (7.76 long tons; 8.69 short tons). An earlier estimate by John S. McIntosh and his colleagues in 1997, found that Patagosaurus was approximately 15 m (49 ft) long, and also 9.44 metric tons (10.41 short tons; 9.29 long tons) in weight, similar to the later estimates by Holtz. A 2006 study by Donald M. Henderson calculated the weight of Patagosaurus to be 7.89 t (7.77 long tons; 8.70 short tons), a smaller estimate than McIntosh's.
The skull of Patagosaurus is not very well known, with a 2003 revision by Oliver Rauhut determining only a few jaws are certainly referrable to it, as opposed to nearly the entire skull. MPEF-PV 1670 shows what the morphology of the adult or subadult skull was like, while MACN CH 933 represents a juvenile individual. Based upon how broad, high and short the adult articulated mandibles of Patagosaurus are, its snout would have been short, high and broad as well, a typical feature of most sauropods.
The teeth of Patagosaurus are reminiscent of more derived sauropods. They are similar in morphology to Euhelopus, being concave on one side as well as having crowns with fairly great expansions. They are also similar to Camarasaurus, although the latter genus has less of a concavity and expansion. The teeth also possess marginal denticles on the crown. Based on histological studies, an individual of Patagosaurus would have replaced all its teeth within 58 days, similar to 62 days for Camarasaurus, and 34 days for Diplodocus.
Most of the postcranial skeleton is known in Patagosaurus. The cervical, caudal, and dorsal vertebrae are generally similar to Camarasaurus, although the sacrum possesses many distinct features. The sacrum is well-preserved, showing that Patagosaurus possessed five sacral vertebrae. All the vertebrae but the fifth are fused together. All the neural spines are tall, and the centra are occasionally transversely narrow. The neural canal of the vertebrae is unique among sauropods however. Starting from the very end of the first vertebra, and extending to almost the end of the third there is an enlargement of the canal, forming a well-defined cavity. Even though the sacrum itself is distinguishing, its sacral ribs resemble Camarasaurus. The sacral vertebrae have a total length of 540 mm (21 in), with the total sacral length being 920 mm (36 in).
The pelvic girdle is well-preserved and well studied. In the holotype, the pelvic girdle is almost complete, only lacking the proximal ends of each ischium. The ilia of the holotype are well known, and show many distinct features. The pubic peduncle, where the ilium articulates with the pubis, is long and straight and has an expansion on the end, as in many sauropods. The upper edge of the iliac blade is curved and thick, with rugosities (rough spots) for cartilage attachment. The pubic elements are large and robust in adults, more so than in juveniles. They are flat when viewed from in front, and convex when seen from behind. Lapparentosaurus resembles Patagosaurus when comparing their pubes. The ischia are much more gracile than the pubes, and only have a small distal expansion. While the ilia resemble Barapasaurus, and the pubes resemble Lapparentosaurus, the ischia are most similar to Diplodocus and Apatosaurus.
The hindlimbs of Patagosaurus are based on scant material, some femora, a tibia, and a few nondescript pedal bones. Two femora come from an adult, with a single additional bone known from the juvenile. The adult femora are proportionately different from the juvenile, being mostly straighter and more ovoid in cross-section. The femoral head is well preserved, although lacking the greater trochanter. The distal end is rather symmetrical when viewed from behind, with two similarly sized condylar surfaces. In the juvenile, the fourth trochanter is completely in the proximal end. The tibia has a well-developed cnemial crest, and is also short and robust. The surface that would have articulated with the astragalus in life has the anterior half raised, and the posterior half lowered.
The pectoral girdle is well known. Both the left and right scapulae and coracoids are known, though incomplete. The scapulae are large, and robust, and thicken as they near the glenoids. The scapular blades are flat, although they are both convex along the anterior edge. Where the scapulae and coracoids articulate, the coracoids are thickest, and they become gradually thinner as they gain distance from the scapulae. The younger specimen of Patagosaurus possesses a slightly different morphology of the pectoral girdle, with slightly differing proportions, such as a slightly smaller scapular blade. The coracoids resemble Barapasaurus in shape, and differ from Camarasaurus, although they cannot be directly compared with those of Cetiosaurus.
The forelimbs of Patagosaurus are only based on three bones from the juvenile specimen, and no manual elements are preserved. The humeri are slender and elongate, lacking great proximal and distal expansions. The incomplete deltoid crest, only shows that it was wide, and likely had a projection below and behind. Like the humeri, the radius is slender, and lacks large expansions on either end. On the edge closest to the ulna, the radius possesses a ridge along its edge, which corresponds to where radioulnar ligaments would have attached. The ulna is complete, although sediment-filled breaks might have altered its original shape. The forelimb of Patagosaurus is much more gracile and different from the robust later sauropods like Camarasaurus, and Apatosaurus, and instead resembles more Diplodocus.
When originally described, Patagosaurus was identified as a relative of Cetiosaurus in the family Cetiosauridae. It can be distinguished from Cetiosaurus, a similar genus, by features of the ischium and vertebrae. Another genus also identified as a cetiosaurid by Bonaparte, Volkheimeria, was named in the same paper as Patagosaurus. Features uniting the genera were identified in the pelvic structure and vertebrae, specifically the caudal neural spines and the ilium and ischium. These characteristics show that the genera are more derived than Amygdalodon, yet more primitive than Haplocanthosaurus.
Later in 1995, Paul Upchurch published a paper on early sauropods, finding Patagosaurus as a cetiosaurid again. He found that although earlier works had distinguished two groups, the shunosaurines and cetiosaurines, in the family, but that Shunosaurus and relatives were actually closer to Euhelopus, and cetiosaurines (Cetiosaurus, Patagosaurus and Amygdalodon) were the only true cetiosaurids. Upchurch noted however that further work on the group might reveal different conclusions.
In a 2009 revision of Euhelopus, Jeffrey A. Wilson and Upchurch published a joint analysis on primitive eusauropodan relationships. They found that Patagosaurus was in fact not a sister taxon of Cetiosaurus, but instead more basal than the genus, effectively invalidating Cetiosauridae. Their results are shown below:
Patagosaurus was uncovered in the Middle Jurassic Cañadón Asfalto Formation, which preserves a large variety of flora and fauna. In fact, Escapa et al. noted that "the fossil record of this formation represents the most completely known biota from the continental Middle to Late Jurassic of the Southern Hemisphere and one of the most complete of the entire world". The Cañadón Asfalto Formation, which was deposited about 165 to 161 million years ago, was a lush ecosystem, in which many organisms lived. In the Middle Jurassic, the region would have been part of the great southern landmass of Gondwana. Most of the plants are conifers, although ferns and equisetales are also abundant. Directly below the formation is a layer of ash, indicating a nearby volcano.
The fauna is dominated by tetrapods, ranging from aquatic amphibians to terrestrial turtles, mammals, and dinosaurs. The sole amphibian known is Notobatrachus; turtles are represented by a distinct form that was named Condorchelys; mammals are known from a few genera, including Argentoconodon, Asfaltomylos, and Henosferus; multiple dinosaurs have been identified, including the sauropods Volkheimeria, Patagosaurus, and a potential third genus that is yet unnamed, and theropods include the related Piatnitzkysaurus and Condorraptor.
Austrosaurus (meaning "Southern lizard") was an extinct genus of sauropod dinosaur from the Allaru Formation and Winton Formation, from the early Cretaceous (110-105 million years ago) of Central-Western Queensland in Australia.Cetiosauridae
Cetiosauridae is a family of sauropod dinosaurs. While traditionally a wastebasket taxon containing various unrelated species, some recent studies have found that it may represent a natural clade. Additionally, at least one study has suggested that the mamenchisaurids may represent a sub-group of the cetiosaurids, which would be termed Mamenchisaurinae.Daxiatitan
Daxiatitan is a genus of titanosaur dinosaur from the Lower Cretaceous of Lanzhou Basin, Gansu Province, northwestern China. It is known from fossils including several neck vertebrae, a shoulder blade, and a thigh bone.It was a very large dinosaur, estimated at 23–30 meters (75–98 feet). Like both Euhelopus and Huanghetitan, it had an enormously long neck.Eusauropoda
Eusauropoda (meaning "true sauropods") 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 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 the distribution of some of these shared derived traits that distinguish Eusauropoda is still completely clear.Ferganasaurus
Ferganasaurus was a genus of dinosaur first formally described in 2003 by Alifanov and Averianov. The type species is Ferganasaurus verzilini. It was a sauropod similar to Rhoetosaurus. The fossils were discovered in 1966 in Kyrgyzstan from the Balabansai Formation and date to the Callovian stage of the Middle Jurassic.Flagellicaudata
Flagellicaudata is a clade of Dinosauria. It belongs to Sauropoda and includes two families, the Dicraeosauridae and the Diplodocidae.Gravisauria
Gravisauria is a clade of sauropod dinosaurs consisting of some genera, Vulcanodontidae and Eusauropoda.Huangshanlong
Huangshanlong is a genus of mamenchisaurid dinosaurs native to the Anhui province of China. It contains a single species, Huangshanlong anhuiensis. H. anhuiensis represents, along with Anhuilong and Wannanosaurus, one of three dinosaurs fround in Anhui province.Kaijutitan
Kaijutitan (meaning "Kaiju titan" after the type of Japanese movie monsters) is a genus of basal titanosaur dinosaur from the Sierra Barrosa Formation from Neuquén Province in Argentina. The type and only species is Kaijutitan maui.Oceanotitan
Oceanotitan is a genus of titanosauriform sauropod known from the Upper Jurassic Praia da Amoreira-Porto Novo Formation of Portugal. It contains one species, Oceanotitan dantasi.The holotype consists of the scapula, almost all of the pelvis, a complete leg sans the toes, and nine caudals.Pilmatueia
Pilmatueia is a diplodocoid sauropod belonging to the family Dicraeosauridae that lived in Argentina during the Early Cretaceous.Shunosaurus
Shunosaurus, meaning "shu lizard", is a genus of sauropod dinosaur from Early Jurassic (Oxfordian) beds in Sichuan Province in China, approximately 159±2 million years ago. The name derives from "Shu", an ancient name for the Sichuan province.Spinophorosaurus
Spinophorosaurus is a genus of sauropod dinosaur that lived in what is now Niger during the Middle Jurassic period. The first two specimens were excavated in the 2000s by German and Spanish teams under difficult conditions. The skeletons were brought to Europe and digitally replicated, making Spinophorosaurus the first sauropod to have its skeleton 3D printed, and were to be returned to Niger in the future. Together, the two specimens represented most of the skeleton of the genus, and one of the most completely known basal sauropods of its time and place. The first skeleton was made the holotype specimen of the new genus and species Spinophorosaurus nigerensis in 2009; the generic name ("spine-bearing lizard") refers to its spiked osteoderms, and the specific name refers to where it was found. A juvenile sauropod from the same area was later assigned to the genus.
The subadult holotype specimen is estimated to have been around 13 m (43 ft) in length, whereas the paratype was about 14 m (46 ft) long. The shoulder height reached by these individuals was estimated at around 4 m (13 ft), and the weight at about 7 metric tons (7.7 short tons). The braincase was short, deep, and broad, and the neuroanatomy was in some ways intermediate between that of basal sauropodomorphs and the more derived neosauropods. The teeth were spatulate (spoon shaped) and had large spaced denticles at the top of the crown, an ancestral feature in sauropods. The neck of Spinophorosaurus is one of the most completely known among sauropods, containing 13 vertebrae. The dorsal vertebrae had multiple small, air-filled internal chambers, a feature typical of later, more derived sauropods. The tail was powered by strong musculature and had a rear section that was rather rigid due to long and overlapping chevron bones. Osteoderms bearing spikes appear to have been placed on the tail tip in two pairs); a similar feature is seen in the related Shunosaurus.
Spinophorosaurus has been classified as either a very basal sauropod, or inside Eusauropoda, a more derived group. The anatomy, age, and location of specimens indicate that important developments in sauropod evolution may have occurred in North Africa, possibly controlled by climatic zones and plant biogeography. Features of the vestibular apparatus suggest that vision and coordinated eye, head, and neck movements were important in Spinophorosaurus. Due to the completeness of Spinophorosaurus, 3D models have been made of the skeleton, and used to test its range of motion. One study suggests it may have been a high browser, and another examined possible mating postures. The spikes on the tail may have been used for defence. Sutures between the neural arches with the centra of the vertebrae were more complex in the front part of the trunk of Spinophorosaurus, since stresses were probably greatest in that region. Spinophorosaurus is known from the Irhazer Shale, a geological formation thought to be Middle Jurassic in age. It was formed by deposits from rivers and lakes in a great river-valley system.Tambatitanis
Tambatitanis is an extinct genus of titanosauriform dinosaur from the Early Cretaceous (probably early Albian) of Japan. It is known from a single type species, Tambatitanis amicitiae. It was probably around 14 meters long and its mass was estimated at some 4 tonnes. It was a basal titanosauriform and possibly belonged to the Euhelopodidae.Tehuelchesaurus
Tehuelchesaurus (tay-WAYL-chay-SAWR-us) is a genus of dinosaur. It is named in honor of the Tehuelche people, native to the Argentinian province of Chubut, where it was first found.Tengrisaurus
Tengrisaurus (meaning "Tengri lizard") is a genus of lithostrotian sauropod, from the Early Cretaceous (Barremian-Aptian), of the Murtoi Formation, Russia. It was described in 2017 by Averianov & Skutschas. The type species is T. starkovi.Volkheimeria
Volkheimeria (meaning "of Volkheimer") was an eusauropod sauropod dinosaur. It lived during the Middle Jurassic, approximately 160 million years ago. Fossils of Volkheimeria have been found in the Cañadón Asfalto Formation of the Cañadón Asfalto Basin in Patagonia, Argentina. The type (and only known) species, V. chubutensis, was described by José Bonaparte in 1979. Volkheimeria is known from some incomplete postcrania, including a mostly complete pelvis and sacrum, caudal vertebrae and a femur and tibia. Many features of this scant material can distinguish Volkheimeria especially in the pelvic and vertebral regions, such as the very low flat neural spines.Vulcanodontidae
The Early Jurassic sauropod dinosaurs Zizhongosaurus, Barapasaurus, Tazoudasaurus, and Vulcanodon may form a natural group of basal sauropods called the Vulcanodontidae. Basal vulcanodonts include some of the earliest known examples of sauropods. The family-level name Vulcanodontidae was erected by M.R. Cooper in 1984. In 1995 Hunt et al. published the opinion that the family is synonymous with the Barapasauridae. One of the key morphological features specific to the family is an unusually narrow sacrum.Yuanmousaurus
Yuanmousaurus ("Yuanmou lizard") was a sauropod dinosaur from the Middle Jurassic period of China. It is known from incomplete remains, recovered in 2000 from the Zhanghe Formation in Yuanmou County in Yunnan Province. Yuanmousaurus was a relatively large sauropod and may have reached about 17 meters (56 ft) in length. It was a basal member of the Sauropoda, but its exact systematic position is unclear. A recent study placed Yuanmousaurus within the family Mamenchisauridae. The only and type species was Yuanmousaurus jiangyiensis.