Herrerasaurus

Source: Wikipedia, the free encyclopedia.

Herrerasaurus
Temporal range:
Ma
↓
Skeleton replica
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria (?)
Clade: Saurischia (?)
Family: †Herrerasauridae
Genus: †Herrerasaurus
Reig, 1963
Species:
†H. ischigualastensis
Binomial name
†Herrerasaurus ischigualastensis
Reig, 1963
Synonyms
  • Ischisaurus cattoi
    Reig, 1963
  • Frenguellisaurus ischigualastensis
    Novas, 1986

Herrerasaurus is likely a genus of saurischian dinosaur from the Late Triassic period. This genus was one of the earliest dinosaurs from the fossil record. Its name means "Herrera's lizard", after the rancher who discovered the first specimen in 1958 in South America. All known fossils of this carnivore have been discovered in the Ischigualasto Formation of Carnian age (late Triassic according to the ICS, dated to 231.4 million years ago) in northwestern Argentina.[1] The type species, Herrerasaurus ischigualastensis, was described by Osvaldo Reig in 1963[2] and is the only species assigned to the genus. Ischisaurus and Frenguellisaurus are synonyms.

For many years, the classification of Herrerasaurus was unclear because it was known from very fragmentary remains. It was

sauropodomorph, a basal saurischian, or not a dinosaur at all but another type of archosaur. However, with the discovery of an almost complete skeleton and skull in 1988,[3][4] Herrerasaurus has been classified as an early saurischian in most of the phylogenies on the origin and early evolution of dinosaurs.[5][6][7][8][9][10][11][12]

It is a member of the

dinosaurian evolutionary radiation.[13][14]

Discovery

Skull of dinosaur with long jaw, teeth, and hollow head
The most complete skull, specimen PVSJ 407, and left maxilla PVSJ 053

Herrerasaurus was named by

Ischigualasto Formation and date from the late Carnian stage of the Late Triassic period.[16] Reig named a second dinosaur from these rocks in the same publication as Herrerasaurus;[2] this dinosaur, Ischisaurus cattoi, is now considered a junior synonym and a juvenile of Herrerasaurus.[17]

Reig believed Herrerasaurus was an early example of a

prosauropod.[18] In 1972, Peter Galton classified the genus as not diagnosable beyond Saurischia.[19] Later, using cladistic analysis, some researchers put Herrerasaurus and Staurikosaurus at the base of the dinosaur tree before the separation between ornithischians and saurischians.[20][21][22][23] Several researchers classified the remains as non-dinosaurian.[24]

Two other partial skeletons, with skull material, were named Frenguellisaurus ischigualastensis by

theropod. Novas (1992) and Sereno and Novas (1992) examined the Frenguellisaurus remains and found them referable to Herrerasaurus.[26] Ischisaurus cattoi was discovered in 1960 and described by Reig in 1963. Novas (1992) and Sereno and Novas (1992) reviewed its remains and found them also to be referable to Herrerasaurus.[26]

Reconstructed skeleton in Japan

A complete Herrerasaurus skull was found in 1988, by a team of paleontologists led by

ichnological records showing large tridactyl (three-toed) footprints that can be attributed only to a theropod dinosaur. These footprints date from the early Carnian Los Rastros Formation in Argentina, which predates Herrerasaurus by several million years.[34][35]

The study of early dinosaurs such as Herrerasaurus and Eoraptor therefore has important implications for the concept of dinosaurs as a

synapomorphies (common anatomical traits derived from the common ancestor). Later authors proposed additional synapomorphies.[20][21] An extensive study of Herrerasaurus by Sereno in 1992 suggested that of these proposed synapomorphies, only one cranial and seven postcranial features were actually derived from a common ancestor, and that the others were attributable to convergent evolution. Sereno's analysis of Herrerasaurus also led him to propose several new dinosaurian synapomorphies.[4]

Description

Scale diagram showing the holotype specimen (red) and the largest-known specimen (gray), compared in size with a human

Herrerasaurus was a lightly built bipedal carnivore with a long tail and a relatively small head. Adults had skulls up to 56 cm (22 in) long and were up to 6 m (20 ft) in total length[4] and 350 kg (770 lb) in weight.[38] Smaller specimens were about 4.5 m (15 ft) long and weighed about 200 kg (440 lb).[39]

Herrerasaurus was fully bipedal. It had strong hind limbs with short

manus (hand) was elongated. The first two fingers and the thumb ended in curved, sharp claws for grasping prey. The fourth and fifth digits were small stubs without claws.[4][40]

Herrerasaurus displays traits that are found in different groups of dinosaurs, and several traits found in non-dinosaurian archosaurs. Although it shares most of the characteristics of dinosaurs, there are a few differences, particularly in the shape of its hip and leg bones. Its pelvis is like that of saurischian dinosaurs, but it has a bony

centra have an hourglass shape as found in Allosaurus.[38]

Life restoration

Herrerasaurus had a long, narrow skull that lacked nearly all the specializations that characterized later dinosaurs,[41] and more closely resembled those of more primitive archosaurs such as Euparkeria. It had five pairs of fenestrae (skull openings) in its skull, two pairs of which were for the eyes and nostrils. Between the eyes and the nostrils were two antorbital fenestrae and a pair of tiny, 1-centimeter-long (0.39 in) slit-like holes called promaxillary fenestrae.[42]

Herrerasaurus had a flexible joint in the lower jaw that could slide back and forth to deliver a grasping bite.[41] This cranial specialization is unusual among dinosaurs but has evolved independently in some lizards.[43] The rear of the lower jaw also had fenestrae. The jaws were equipped with large serrated teeth for biting and eating flesh, and the neck was slender and flexible.[17][41]

According to Novas (1993), Herrerasaurus can be distinguished based on the following features:

peduncle forms a right angle with the dorsal border of the shaft on the ischium
.

According to Sereno (1993), Herrerasaurus can be distinguished based on the following features, all of which are unknown in other herrerasaurids:

humeral ectepicondyle, a feature also present in Saturnalia; a saddle-shaped ulnar condyle of the humerus, and the articular surface for the ulnare on the ulna is convex; the articular surface of the ulnare is smaller than that of the ulna, a feature unknown in Staurikosaurus and Sanjuansaurus; the centrale is placed distal to the radiale; a broad subnarial process of the premaxilla, and a broad supratemporal depression (noted by Sereno and Novas, 1993);[46] the basal tuber and the occipital condyle are subequal in width (noted by Sereno and Novas, 1993).[46]

Classification

Skeletal diagram

Herrerasaurus was originally considered to be a genus within

Teratosauridae. In 1970, Bonaparte also proposed similarities between Herrerasaurus and Staurikosaurus, and while classifying them both clearly as in Saurischia, he stated that they appeared as though they could not be placed in a current family. This was further supported by Benedetto in 1973, who named for the taxa the new family Herrerasauridae, which he classified as saurischians, possibly within Theropoda but not in Sauropodomorpha.[50] However, in 1977 Galton proposed that Herrerasauridae only included Herrerasaurus, and found it to be Saurischian incertae sedis.[51]

Proposed in 1987 by Brinkman and Sues, Herrerasaurus has at times been considered basal to

Herrerasauria was named by Galton in 1985, and defined as Herrerasaurus but not Liliensternus or Plateosaurus by Langer (2004), who used the node-based definition for Herrerasauridae.[53]

Life restoration

In a revision of basal Dinosauria, Padian and May (1993) discussed the definition of the clade, and redefined it as the latest common ancestor of Triceratops and birds. They also discussed what this definition would do to the most basal taxa, such as Herrerasauridae, and Eoraptor. Padian and May considered that since both Herrerasauridae and Eoraptor lack many diagnostic features of Saurischia or Ornithischia, that they could not be considered inside Dinosauria.[54]

A later 1994 study by Novas instead classified Herrerasaurus within Dinosauria, and strongly supported its position within Saurischia, as well as provided synapomorphies that it shared with Theropoda. Novas found that the primitive features of lacking a brevis fossa and having only two sacral vertebrae were simply reversals found in the genus.

phylogenetic analysis, which placed it closer to Neotheropoda than Eoraptor or Sauropodomorpha.[56] Langer (2004) mentioned that this hypothesis was widely accepted, but that more later authors instead preferred to place Herrerasaurus as well as Eoraptor basal to Theropoda and Sauropodomorpha, a clade called Eusaurischia. Langer (2004) conducted a phylogenetic analysis, and found that it was much more likely that Herrerasaurus was a basal saurischian, than either a theropod or a non-dinosaurian.[53] Langer's proposal was supported by multiple studies until the discovery of Tawa, when Nesbitt et al. conducted a more inclusive analysis, and the resulting cladogram placed Herrerasauridae basal to Eoraptor, but closer to Dilophosaurus than Sauropodomorpha.[57][58] Unlike Nesbitt, Ezcurra (2010) conducted a phylogenetic analysis to place his new taxon Chromogisaurus, and found that Herrerasauridae was basal to Eusaurischia.[59]

In 2010, Alcocer and Martinez described a new taxon of herrerasaurid, Sanjuansaurus. It could be distinguished from Herrerasaurus based on multiple features. In the phylogenetic analysis, Herrerasaurus, Sanjuansaurus and Staurikosaurus all were in a polytomy, and Herrerasauridae was the most primitive group of saurischian, outside Eusaurischia, Eoraptor and Guaibasaurus.[1] In 2011, Martinez et al. described Eodromaeus, a basal theropod from the same formation as Herrerasaurus. In a phylogenetic analysis, Eoraptor was placed within Sauropodomorpha, Herrerasauridae was placed as the most basal theropods, and Eodromaeus was placed as the next most basal.[60] A more recent analysis, by Bittencourt et al. (2014), placed Herrerasauridae in a polytomy with Theropoda and Sauropodomorpha, with Eoraptor also being in an unresolved position. This cladogram is shown below.[61]

Herrerasaurus (large), Eoraptor (small), and Plateosaurus (skull), three early saurischians
Dinosauria

Other members of the

Teyuwasu, known from very fragmentary remains from the Late Triassic of Brazil, might be related.[65] Paul (1988) noted that it had been incorrectly suggested that Staurikosaurus pricei was a juvenile Herrerasaurus. This claim was refuted when pelvic bones from a juvenile Herrerasaurus were discovered, which upon examination did not resemble the pelvic bones of Staurikosaurus.[38]

Paleobiology

Reconstructed skull in the Natural History Museum in Milan

The teeth of Herrerasaurus indicate that it was a

synapsids.[66] Herrerasaurus itself may have been preyed upon by giant "rauisuchians" (loricatans) like Saurosuchus; puncture wounds were found in one skull.[41]

Coprolites (fossilized dung) containing small bones but no trace of plant fragments, discovered in the Ischigualasto Formation, have been assigned to Herrerasaurus based on fossil abundance. Mineralogical and chemical analysis of these coprolites indicates that if the referral to Herrerasaurus was correct, this carnivore could digest bone.[67]

synapsid

Comparisons between the

cathemeral, active throughout the day at short intervals.[68]

In a 2001 study conducted by Bruce Rothschild and other paleontologists, 12 hand bones and 20 foot bones referred to Herrerasaurus were examined for signs of stress fracture, but none were found.[69]

PVSJ 407, a Herrerasaurus ischigualastensis, had a pit in a skull bone attributed by Paul Sereno and Novas to a bite. Two additional pits occurred on the splenial. The areas around these pits are swollen and porous, suggesting the wounds were afflicted by a short-lived non-lethal infection. Because of the size and angles of the wound, it is likely that they were obtained in a fight with another Herrerasaurus.[70]

Paleoecology

Model depicted with prey

The holotype of Herrerasaurus (PVL 2566) was discovered in the Cancha de Bochas Member of the Ischigualasto Formation in San Juan, Argentina. It was collected in 1961 by Victorino Herrera, in sediments that were deposited in the Carnian stage of the Triassic period, approximately 231 to 229 million years ago.[71] Over the years, the Ischigualasto Formation produced other fossils ultimately referred to Herrerasaurus. In 1958, A.S. Romer discovered specimen MCZ 7063, originally referred to Staurikosaurus in Carnian sediments. Herrerasaurus specimens PVL 2045 and MLP(4)61, were collected in 1959 and 1960, respectively, in sediments that were deposited in the Norian stage of the Triassic period, approximately 228 to 208 million years ago. However, these specimens are no longer regarded as pertaining to Herrerasaurus.[5][72][73] In 1960, Scaglia collected specimen MACN 18.060, originally the holotype of Ischisaurus cattoi, in sediments deposited in the Carnian stage. In 1961, Scaglia collected Herrerasaurus specimen PVL 2558, in the Carnian beds of this formation. In 1990, the Cancha de Bochas Member produced more Herrerasaurus specimens, also from its Carnian beds.[74] Specimen PVSJ 53, originally the holotype of Frenguellisaurus ischigualastensis, was collected by Gargiulo & Oñate in 1975 in sediments that were deposited in the Carnian stage.[10]

Although Herrerasaurus shared the body shape of the large carnivorous dinosaurs, it lived during a time when dinosaurs were small and few. It was the time of non-dinosaurian reptiles, not dinosaurs, and a major turning point in the Earth's ecology. The vertebrate fauna of the Ischigualasto Formation and the slightly later

synapsids.[72] In the Ischigualasto Formation, dinosaurs constituted only about 10% of the total number of fossils,[60][72] but by the end of the Triassic Period, dinosaurs were becoming the dominant large land animals, and the other archosaurs and synapsids declined in variety and number.[75]

Studies suggest that the

horsetails, and giant conifers (Protojuniperoxylon).[78] These plants formed lowland forests along the banks of rivers.[4] Herrerasaurus remains appear to have been the most common among the carnivores of the Ischigualasto Formation.[16] It lived in the jungles of Late Triassic South America alongside other early dinosaurs, such as Sanjuansaurus, Eoraptor, Panphagia, and Chromogisaurus, as well as rhynchosaurs (Scaphonyx), cynodonts (e.g., Exaeretodon, Ecteninion and Chiniquodon), dicynodonts (Ischigualastia), pseudosuchians (e.g., Saurosuchus, Sillosuchus and Aetosauroides), proterochampsids (e.g., Proterochampsa) and temnospondyls (Pelorocephalus).[5][72]

References

  1. ^
    PMID 21594020
    .
  2. ^ a b c d Reig, O.A. (1963). "La presencia de dinosaurios saurisquios en los "Estratos de Ischigualasto" (Mesotriásico Superior) de las provincias de San Juan y La Rioja (República Argentina)". Ameghiniana (in Spanish). 3 (1): 3–20.
  3. doi:10.1080/02724634.1988.10011734
    .
  4. ^
    S2CID 1640394
    .
  5. ^
    ISSN 0895-9811
    .
  6. PMID 27839975
    .
  7. ISSN 0024-4082
    .
  8. PMID 32842895
    .
  9. S2CID 232313141
    .
  10. ^
    ISBN 978-0-520-24209-8
    .
  11. PMID 30785940
    .
  12. S2CID 182843217
    .
  13. S2CID 8349110
    ..
  14. ^ Airhart, Marc (December 10, 2009). "New Meat-Eating Dinosaur Alters Evolutionary Tree". Jackson School of Geosciences. Archived from the original on March 10, 2010.
  15. S2CID 4270484
    .
  16. ^
    S2CID 35644127
    .
  17. ^
    doi:10.1080/02724634.1994.10011523
    .
  18. ^ Steel, R. (1970). "Part 14. Saurischia. Handbuch der Paläoherpetologie/Encyclopedia of Paleoherpetology". Gustav Fischer Verlag, Stuttgart: 1–87.
  19. S2CID 84931897
    .
  20. ^ a b c Brinkman, D.B.; Sues, H.D. (1987). "A staurikosaurid dinosaur from the Upper Triassic Ischigualasto Formation of Argentina and the relationships of the Staurikosauridae" (PDF). Palaeontology. 30 (3): 493–503. Archived from the original (PDF) on December 8, 2015. Retrieved October 20, 2015.
  21. ^ a b c Novas, F.E. (1992). "Phylogenetic relationships of the basal dinosaurs, the Herrerasauridae" (PDF). Palaeontology. 35 (1): 51–62. Archived from the original (PDF) on December 8, 2015. Retrieved October 20, 2015.
  22. doi:10.1080/02724634.1984.10012026
    .
  23. S2CID 132827962
    .
  24. ^ Gauthier, J.A.; Cannatella, D.; Queiroz, K.; Kluge, A.G. & Rowe, T. (1989). "Tetrapod phylogeny". In B. Fernholm; K. Bremer & Jörnvall, H. (eds.). The Hierarchy of Life. Amsterdam: Elsevier Science Publishers B. V. pp. 337–353.
  25. ^ Novas, F. E. (1986). "Un probable terópodo (Saurischia) de la Formación Ischigualasto (Triásico superior), San Juan, Argentina". IV Congreso Argentino de Paleontología y Bioestratigrafía, Mendoza, November 23–27 (in Spanish). 2: 1–6.
  26. ^
    S2CID 1640394
    .
  27. ^ Holtz, T.R. Jr.; Padian, K. (1995). "Definition and diagnosis of Theropoda and related taxa". Journal of Vertebrate Paleontology. 15 (3, supplement): 35A.
  28. ^ Bonaparte, J.F.; Pumares, J.A. (1995). "Notas sobre el primer cráneo de Riojasaurus incertus (Dinosauria, Prosauropoda, Melanorosauridae) del Triásico superior de La Rioja, Argentina". Ameghiniana (in Spanish). 32: 341–349.
  29. ^ Rauhut, O.W.M. (2003). "The interrelationships and evolution of basal theropod dinosaurs". Special Papers in Palaeontology. 69: 1–213.
  30. S2CID 220415208
    .
  31. S2CID 55723635
    .
  32. S2CID 6050601
    .
  33. S2CID 8349110. Archived from the original
    on July 11, 2007. Retrieved July 20, 2007.
  34. doi:10.1080/02724634.1995.10011277
    .
  35. ^ Arcucci, A. C.; Forster, C.; May, C.; Abdala, F.; Marsicano, C. (1998). "Una nueva icnofauna de la Formación Los Rastros, Triásico Medio, en la Quebrada de Ischichuca Chica (Provincia de La Rioja, Argentina)". Acta Geológica Lilloana (in Spanish). 18: 152.
  36. S2CID 4220935
    .
  37. ^ Bonaparte, J. F. (1976). "Pisanosaurus mertii Casimiquela and the origin of the Ornithischia". Journal of Paleontology. 50: 808–820.
  38. ^
    ISBN 978-0-671-68733-5
    .
  39. OCLC 985402380
    .
  40. doi:10.1080/02724634.1994.10011524
    .
  41. ^
    doi:10.1080/02724634.1994.10011525
    .
  42. S2CID 84270944
    .
  43. ^ McDowell, S.B. Jr.; Bogert, C.M. (1954). "The systematic position of Lanthanotus and the affinities of the anguinomorphan lizards". Bulletin of the American Museum of Natural History. 105: 1–142.
  44. doi:10.1080/02724634.1994.10011523
    .
  45. doi:10.1080/02724634.1994.10011524
    .
  46. ^
    doi:10.1080/02724634.1994.10011525
    .
  47. hdl:2027/uiug.30112032536010
    .
  48. S2CID 86687464. Archived from the original
    (PDF) on September 24, 2015.
  49. doi:10.1098/rstb.1985.0092
    .
  50. ^ Benedetto, J.L. (1973). "Herrerasauridae, nueva familia de saurisquios triasicos" (PDF). Ameghiniana. 10 (1): 89–102.
  51. S2CID 129438498
    .
  52. doi:10.1127/njgpa/210/1998/41
    .
  53. ^
    ISBN 978-0-520-25408-4
    .
  54. ^ Padian, K.; May, C.L. (1993). "The Earliest Dinosaurs". In Lucas, Spencer G.; Morales, M. (eds.). The Nonmarine Triassic. New Mexico Museum of Natural History & Science Bulletin 3. pp. 379–381. Retrieved February 21, 2024 – via Google Books.
  55. doi:10.1080/02724634.1994.10011523
    .
  56. JSTOR 4523770
    .
  57. S2CID 34530296
    .
  58. S2CID 8349110
    .
  59. S2CID 129244872
    .
  60. ^
    S2CID 33506648
    .
  61. S2CID 56155733
    .
  62. ^ Long, R.A.; Murry, P.A. (1995). "Late Triassic (Carnian and Norian) Tetrapods from the Southwestern United States". New Mexico Museum of Natural History and Science, Bulletin. 4: 1–254.
  63. doi:10.1016/S0016-6995(98)80123-X
    .
  64. doi:10.1080/02724634.1994.10011546
    .
  65. ^ Kischlat, E.-E. (1999). "A new dinosaurian "rescued" from the Brazilian Triassic: Teyuwasu barberenai, new taxon". Paleontologia Em Destaque, Boletim Informativo da Sociedade Brasileira de Paleontologia. 14 (26): 58.
  66. ISBN 978-0-520-06726-4
    .
  67. S2CID 131242248
    .
  68. S2CID 33253407
    .
  69. ^ Rothschild, B., Tanke, D. H., and Ford, T. L., 2001, Theropod stress fractures and tendon avulsions as a clue to activity: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 331–336.
  70. ^ Molnar, R. E., 2001, Theropod paleopathology: a literature survey: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 337–363.
  71. ISSN 0895-9811
    .
  72. ^
    S2CID 37918101
    .
  73. S2CID 135096489
    .
  74. S2CID 4270484
    .
  75. ISBN 978-0-253-21313-6
    .
  76. doi:10.1016/0031-0182(82)90034-7. Archived from the original
    (PDF) on January 26, 2009. Retrieved July 23, 2009.
  77. ^ Columbi, Carina E. (October 5, 2008). Stable isotope analysis of fossil plants from the Upper Triassic Ischigualasto Formation in the northwest of Argentina. Houston, Texas: The Geological Society of America. Archived from the original on January 11, 2012. Retrieved July 23, 2009.
  78. ^ Bonaparte, J.F. (1979). "Faunas y paleobiogeografía de los tetrápodos mesozoicos de América del Sur". Ameghiniana, Revista de la Asociación Paleontológica Argentina (in Spanish). 16 (3–4): 217–238.

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Herrerasaurus&oldid=1219745349"