Brachychampsa

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Brachychampsa
Temporal range: Late Cretaceous, 72.1–66  Ma [1]
Brachychampsa sp. - Natural History Museum of Utah - DSC07238.JPG
Brachychampsa sp.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Clade: Archosauriformes
Order: Crocodilia
Clade: Globidonta
Family: Alligatoridae
Genus:† Brachychampsa
Gilmore, 1911 [2]
Species
  • †B. montanaGilmore, 1911 (type) [2]
  • †B. perrugosus(Cope, 1875)
  • †?B. sealeyiWilliamson, 1996 [3]

Brachychampsa is an extinct genus of alligatorid, possibly a basal caiman. [4] Specimens have been reported from New Mexico, Colorado, Wyoming, [5] Montana, [2] [6] [7] North and South Dakota, [8] New Jersey, and Saskatchewan, though only those from Montana, Utah, and New Mexico are based on material sufficient to justify the referral. Some specimens have been reported from the Campanian-aged deposits of Central Asia (Chimkent of Kazakhstan and Kirkuduk of Tajikistan), although the species status is indeterminate for these fossils. [9] [10] The genus first appeared during the late Campanian stage of the Late Cretaceous (Judithian North American stage) and became extinct during the late Maastrichtian stage of the Cretaceous (Lancian North American Land Mammal "Age"). Brachychampsa is distinguished by an enlarged fifth maxillary tooth in the upper jaw.

Contents

Life reconstruction of Brachychampsa montana Brachychampsa NT small.jpg
Life reconstruction of Brachychampsa montana
Skull Brachychampsa sp. - Natural History Museum of Utah - DSC07244.JPG
Skull

Taxonomy

The type species of Brachychampsa is B. montana, first discovered from the Hell Creek Formation of Montana and described by Charles W. Gilmore in a paper in 1911. In that same paper, Gilmore recombined Bottosaurus perrugosus as a new species of Brachychampsa, called B. perrugosus. [2] The holotype specimen of B. perrugosus went missing as the paper was being written, but it was later rediscovered and soon afterward designated as a nomen dubium due to a lack of diagnostic features that distinguish it from other alligatorids discovered since the paper was published. [11] Another species from the Allison Member of the Menefee Formation of the San Juan Basin, B. sealeyi, was discovered in 1996, [3] but was later argued to be synonymous with B. montana by interpreting it as an immature specimen of the latter species. [12] However, other studies have shown that some of the variation seen between the two species, such as the orientation of the maxillary tooth row, are not ontogenic, thus making B. sealeyi a valid taxon. [13]

Phylogeny

Brachychampsa's position within Alligatoroidea has undergone many revisions since it was first named. Originally it was placed within Alligatoridae, and was later refined to the Alligatorinae in 1964, [5] only to be placed outside both Alligatorinae and Alligatoridae (but still within Alligatoroidea) in 1994. [11] Accordingly, studies have shown Brachychampsa as a basal member of Alligatoroidea, within the clade Globidonta, [14] [15] as shown in the cladogram below. [15]

Alligatoroidea

Alternatively, other phylogenetic studies have recovered Brachychampsa as an alligatorid, specifically as a stem-caiman, [16] [17] as shown in the cladogram below. [16]

Alligatoroidea
(stem-based group)

However, Walter et al. (2022) recovered Brachychampsa, Stangerochampsa and Albertochampsa as the basalmost alligatorines based on phylogenetic analysis and claimed that the earliest definitive stem-group caimans are known from the earliest Paleocene. [18]

Palaeoecology

Brachychampsa's dentition was heterodont, with conical teeth at the front and bulbous teeth at the back. [19] It has been regarded as a specialist hunter of turtles, based on its rostral shape, massive dentary, and dental morphology, [20] though this has been challenged over the years. A more generalist diet of small invertebrates and vertebrates has also been proposed. [21] In 2003, Robert M. Sullivan and Spencer G. Lucas observed that most late Cretaceous turtles were probably too big for consumption, and that if they did represent a large portion of Brachychampsa's diet, it would have had to hunt either juveniles or smaller turtle species. [22]

Related Research Articles

<span class="mw-page-title-main">Alligatoridae</span> Family of crocodilians including alligators, caimans and kin

The family Alligatoridae of crocodylians includes alligators, caimans and their extinct relatives.

<i>Ceratosuchus</i> Extinct genus of reptiles

Ceratosuchus is an extinct genus of alligatorine crocodylian from latest Paleocene rocks of Colorado's Piceance Basin and earliest Eocene rocks of Wyoming's Bighorn Basin in North America, a slice of time known as the Clarkforkian North American Land Mammal Age. Like its modern relatives, Ceratosuchus was a swamp-dwelling predator. It is named for the pair of flattened, triangular bony plates that extend from the back of its head.

Wannaganosuchus is an extinct genus of small alligatorid crocodilian. It was found in Late Paleocene-age rocks of Billings County, North Dakota, United States.

Albertochampsa is an extinct genus of alligatorid from the Late Cretaceous of Alberta. It was named in 1972 by Bruce Erickson, and the type species is A. langstoni. It is known from a skull from the Campanian-age Dinosaur Park Formation, where it was rare; Leidyosuchus is the most commonly found crocodilian at the Park. The skull of Albertochampsa was only about 21 cm long (8.3 in).

<i>Procaimanoidea</i> Extinct genus of reptiles

Procaimanoidea is an extinct genus of alligatorid from the Eocene of North America. It was named posthumously in 1946 by Charles W. Gilmore; the type species is P. utahensis, from the Uintan of Utah. It is based on USNM 15996, a nearly complete skull and partial left hind leg. A second species, P. kayi, was named in 1941 by C.C. Mook as a species of Hassiacosuchus, for remains from the Bridgerian of Wyoming. It was reassigned to Procaimanoidea in 1967 by Wassersug and Hecht.

<i>Leidyosuchus</i> Genus of reptiles

Leidyosuchus is an extinct genus of alligatoroid from the Late Cretaceous of Alberta. It was named in 1907 by Lawrence Lambe, and the type species is L. canadensis. It is known from a number of specimens from the middle Campanian age Dinosaur Park Formation. It was a medium-sized alligatoroid, with a maximum skull length greater than 40 centimeters (16 in).

<span class="mw-page-title-main">Caiman</span> Subfamily of reptiles

A caiman is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans are native to Central and South America and inhabit marshes, swamps, lakes, and mangrove rivers. They have scaly skin and live a fairly nocturnal existence. They are relatively small-sized crocodilians with an average maximum weight of 6 to 40 kg depending on species, with the exception of the black caiman, which can grow more than 4 m (13 ft) in length and weigh in excess of 450 kg. The black caiman is the largest caiman species in the world and is found in the slow-moving rivers and lakes that surround the Amazon basin. The smallest species is the Cuvier's dwarf caiman, which grows to 1.2 to 1.5 m long. There are six different species of caiman found throughout the watery jungle habitats of Central and Southern America. The average length for most of the other caiman species is about 2 to 2.5 m long.

<span class="mw-page-title-main">Alligatorinae</span> Subfamily of reptiles

Alligatorinae is a subfamily within the family Alligatoridae that contains the alligators and their closest extinct relatives, and is the sister taxon to Caimaninae. Many genera in Alligatorinae are described, but only the genus Alligator is still living, with the remaining genera extinct.

<span class="mw-page-title-main">Alligatoroidea</span> Superfamily of reptiles

Alligatoroidea is one of three superfamilies of crocodylians, the other two being Crocodyloidea and Gavialoidea. Alligatoroidea evolved in the Late Cretaceous period, and consists of the alligators and caimans, as well as extinct members more closely related to the alligators than the two other groups.

<i>Allognathosuchus</i> Extinct genus of reptiles

Allognathosuchus is an extinct genus of alligatorine crocodylian with a complicated taxonomic history. It was named in 1921.

<i>Navajosuchus</i> Extinct genus of reptiles

Navajosuchus is an extinct genus of alligatorine crocodylian. Its fossils have been found in the Paleocene-age Nacimiento Formation of the San Juan Basin, New Mexico. It was named in 1942 by Charles C. Mook, and the original type species was N. novomexicanus. N. novomexicanus was based on AMNH 5186, a partial skull collected in 1913. Later research showed that Navajosuchus novomexicanus was the same as the earlier-named Allognathosuchus mooki. However, A. mooki does not belong to the genus Allognathosuchus, and so the name of the crocodilian becomes Navajosuchus mooki. Under whichever name is used, this animal would have been a generalized predator of the Nacimiento floodplains. It was the most common Nacimiento Formation crocodilian, found in both the Puercan and Torrejonian faunal assemblages.

<i>Acynodon</i> Extinct genus of reptiles

Acynodon is an extinct genus of eusuchian crocodylomorph from the Late Cretaceous, with fossils found throughout Southern Europe.

Arambourgia is an extinct monotypic genus of alligatorine crocodylian from Europe. It was named in 1905 as Allognathosuchus gaudryi. It was made a separate genus Arambourgia in 1940. This was synonymized with Allognathosuchus haupti in 1990, but later reassigned as its own genus once again in 2004. Arambourgia was likely to have been part of an early dispersal event of alligatorines from North America to Europe during the Eocene epoch. Arambourgia had non-serrated teeth and a deep orienirostral snout, unlike the flatter snouts of most other alligatorids.

Bottosaurus is an extinct genus of alligatorid from the Late Cretaceous-Early Paleocene of New Jersey, Texas, and possibly North Carolina and South Carolina. Two species are currently accepted, with a third requiring re-evaluation.

<i>Musturzabalsuchus</i> Extinct genus of reptiles

Musturzabalsuchus is an extinct monospecific genus of allodaposuchid eusuchian crocodyliform. The type and only species is Musturzabalsuchus buffetauti.

<i>Stangerochampsa</i> Extinct genus of reptiles

Stangerochampsa is an extinct genus of alligatorid, possibly an alligatorine or a stem-caiman, from the Late Cretaceous of Alberta. It is based on RTMP.86.61.1, a skull, partial lower jaws, and partial postcranial skeleton discovered in the late Campanian–early Maastrichtian-age Horseshoe Canyon Formation. Stangerochampsa was described in 1996 by Wu and colleagues. The type species is S. mccabei. The generic name honors the Stanger family, the owners of the ranch where the specimen was found, and the species name honors James Ross McCabe, who discovered, collected, and prepared it. Stangerochampsa is described as "small to medium–sized"; the type skull is 20.0 centimetres (7.9 in) long from the tip of the snout to the occipital condyle, and is 13.0 centimetres (5.1 in) wide at its greatest, while the thigh bone is 14.2 centimetres (5.6 in) long. It had heterodont dentition, with large crushing teeth at the rear of the jaws.

<span class="mw-page-title-main">Globidonta</span> Clade of reptiles

Globidonta is a clade of alligatoroids that includes alligators, caimans, and closely related extinct forms. It is defined as a stem-based clade including Alligator mississippiensis and all forms more closely related to it than to Diplocynodon. The group's fossil range extends back into the Campanian stage of the Late Cretaceous with early alligatoroids such as Albertochampsa and Brachychampsa. Extinct globidontans were particularly common in North America and Eurasia, and their modern range also includes South America.

Culebrasuchus is an extinct, monotypic genus of caiman alligatorid known from the Early to Middle Miocene (Hemingfordian) of the Panama Canal Zone of Panama. It contains a single species, Culebrasuchus mesoamericanus.

Globidentosuchus is an extinct genus of basal caimanine crocodylian known from the late Middle to Late Miocene of the Middle and the Upper Members of the Urumaco Formation at Urumaco, Venezuela. Its skull was very short and robust, with large units of spherical teeth used to break the shells of molluscs as part of its durophagus diet. It is thought to be one of the most basal Caimanines, even sharing some traits with alligatorids.

<i>Menefeeceratops</i> Extinct genus of dinosaurs

Menefeeceratops is a genus of ceratopsid dinosaur from the Menefee Formation in New Mexico, United States. It is potentially the oldest known member of the ceratopsids, as well as the centrosaurine subfamily, related to animals including Yehuecauhceratops and Crittendenceratops. The type and only species is Menefeeceratops sealeyi, known from a partial, non-articulated skeleton.

References

  1. ↑ Rio, Jonathan P.; Mannion, Philip D. (6 September 2021). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ . 9: e12094. doi: 10.7717/peerj.12094 . PMC   8428266 . PMID   34567843.
  2. 1 2 3 4 Gilmore, Charles W. (1911). "A new fossil alligator from the Hell Creek Beds of Montana" (PDF). Proceedings of the United States National Museum. 41 (1860): 297–302. doi:10.5479/si.00963801.41-1860.297.
  3. 1 2 Williamson, Thomas E. (1996). "?Brachychampsa sealeyi, sp. nov., (Crocodylia, Alligatoridea) from the Upper Cretaceous (Lower Campanian) Menefee Formation, northwestern New Mexico". Journal of Vertebrate Paleontology . 16 (3): 421–431. doi:10.1080/02724634.1996.10011331. JSTOR   4523734.
  4. ↑ Rio, Jonathan P.; Mannion, Philip D. (2021-09-06). "Phylogenetic analysis of a new morphological dataset elucidates the evolutionary history of Crocodylia and resolves the long-standing gharial problem". PeerJ. 9: e12094. doi: 10.7717/peerj.12094 . ISSN   2167-8359. PMC   8428266 . PMID   34567843.
  5. 1 2 Estes, R. (1964). "Fossil vertebrates from the Late Cretaceous Lance Formation, eastern Wyoming". University of California Publications in Geological Sciences. 49: 1–180.
  6. ↑ Estes, R.; Berberian, P. (1970). "Paleoecology of a Late Cretaceous vertebrate community from Montana". Breviora. 343: 1–35.
  7. ↑ Bryant, L. J. (1989). "Non-dinosaurian lower vertebrates across the Cretaceous-Tertiary boundary in northeastern Montana". University of California Publications in Geological Sciences. 134: 1–107.
  8. ↑ Pearson, Dean A.; Schaefer, Terry; Johnson, Kirk R.; Nichols, Douglas J.; Hunter, John P. (2002). "Vertebrate biostratigraphy of the Hell Creek Formation in southwestern North Dakota and northwestern South Dakota". In Hartman, Joseph Herbert; Johnson, Kirk. R.; Nichols, Douglas J. (eds.). The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the Northern Great Plains. An Integrated Continental Record of the End of the Cretaceous. Vol. 361. Geological Society of America. pp. 145–167. doi:10.1130/0-8137-2361-2.145. ISBN   9780813723617.
  9. ↑ Averianov, A.; Nessov, L. (1995). "A new Cretaceous mammal from the Campanian of Kazakhstan". Neues Jahrbuch für Geologie und Paläontologie - Monatshefte. 2: 65–74. doi:10.1127/njgpm/1995/1995/65.
  10. ↑ Martin, J.E.; Delfino, M. (2010). "Recent advances in the comprehension of the biogeography of Cretaceous European eusuchians". Palaeogeography, Palaeoclimatology, Palaeoecology. 293 (3): 406–418. Bibcode:2010PPP...293..406M. doi:10.1016/j.palaeo.2009.10.021.
  11. 1 2 Norell, M. A.; Clark, J. M.; Hutchison, J. H. (1994). "The Late Cretaceous alligatoroid Brachychampsa montana (Crocodylia): new material and putative relationships". American Museum Novitates (3116): 1–26.
  12. ↑ Sullivan, Robert M.; Lucas, Spencer G. (2003). "Brachychampsa montana Gilmore (Crocodylia, Alligatoroidea) from the Kirtland Formation (upper Campanian), San Juan Basin, New Mexico". Journal of Vertebrate Paleontology . 23 (4): 832–841. doi:10.1671/A1082-8. JSTOR   4524385. S2CID   140631483.
  13. ↑ Brochu, Christopher A. (2004). "Alligatorine phylogeny and the status of Allognathosuchus Mook, 1921". Journal of Vertebrate Paleontology . 24 (4): 857–873. doi:10.1671/0272-4634(2004)024[0857:APATSO]2.0.CO;2. JSTOR   4524781. S2CID   85050852.
  14. ↑ Michael S. Y. Lee; Adam M. Yates (27 June 2018). "Tip-dating and homoplasy: reconciling the shallow molecular divergences of modern gharials with their long fossil". Proceedings of the Royal Society B . 285 (1881). doi: 10.1098/rspb.2018.1071 . PMC   6030529 . PMID   30051855.
  15. 1 2 Tobias Massonne; Davit Vasilyan; Márton Rabi; Madelaine Böhme (2019). "A new alligatoroid from the Eocene of Vietnam highlights an extinct Asian clade independent from extant Alligator sinensis". PeerJ. 7: e7562. doi: 10.7717/peerj.7562 . PMC   6839522 . PMID   31720094.
  16. 1 2 Paula Bona; Martín D. Ezcurra; Francisco Barrios; María V. Fernandez Blanco (2018). "A new Palaeocene crocodylian from southern Argentina sheds light on the early history of caimanines". Proceedings of the Royal Society B: Biological Sciences. 285 (1885): 20180843. doi:10.1098/rspb.2018.0843. PMC   6125902 . PMID   30135152.
  17. ↑ Adam P. Cossette; Christopher A. Brochu (2020). "A systematic review of the giant alligatoroid Deinosuchus from the Campanian of North America and its implications for the relationships at the root of Crocodylia". Journal of Vertebrate Paleontology. 40: e1767638. Bibcode:2020JVPal..40E7638C. doi: 10.1080/02724634.2020.1767638 .
  18. ↑ Walter J, Darlim G, Massonne T, Aase A, Frey E, Rabi M (2022). "On the origin of Caimaninae: insights from new fossils of Tsoabichi greenriverensis and a review of the evidence". Historical Biology. 34 (4): 580–595. doi:10.1080/08912963.2021.1938563. S2CID   238723638.
  19. ↑ Melstrom, Keegan M.; Irmis, Randall B. (2019). "Repeated Evolution of Herbivorous Crocodyliforms during the Age of Dinosaurs". Current Biology . 29 (14) – via CellPress.
  20. ↑ Carpenter, Kenneth; Lindsey, D. (1980). "The dentary of Brachychampsa montana Gilmore (Alligatorinae; Crocodylidae), a Late Cretaceous turtle-eating alligator". Journal of Paleontology. 54 (6): 1213–1217.
  21. ↑ Bartels, William S. (1984). "Osteology and Systematic Affinities of the Horned Alligator Ceratosuchus (Reptilia, Crocodilia)". Journal of Paleontology. 58 (6): 1347–1353. ISSN   0022-3360.
  22. ↑ Sullivan, Robert M.; Lucas, Spencer G. (2003-12-24). "Brachychampsa montana Gilmore (Crocodylia, Alligatoroidea) from the Kirtland Formation (Upper Campanian), San Juan Basin, New Mexico". Journal of Vertebrate Paleontology. 23 (4): 832–841. doi:10.1671/A1082-8. ISSN   0272-4634.
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