Albertochampsa

Albertochampsa is an extinct genus of alligatorid (possibly a stem-caiman^[1] or a basal alligatorine^[2]) from the Late Cretaceous of Alberta. It was named in 1972 by Bruce Erickson, and the type species is A. langstoni.^[3] 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).^[4]

Albertochampsa Temporal range: 76.5–75 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauromorpha
Clade:	Archosauriformes
Order:	Crocodilia
Family:	Alligatoridae
Genus:	†Albertochampsa Erickson, 1972
Type species
†Albertochampsa langstoni Erickson, 1972

Phylogeny

Albertochampsa is a member of the family Alligatoridae, which includes the extant (living) alligators and caimans, although it is disputed whether Albertochampsa is more closely related to the alligators or the caimans. The below cladogram from a 2018 study shows Albertochampsa as more closely related to the caimans in the subfamily Caimaninae.^[5]

Alligatoridae

Alligatorinae (stem-based group) Caimaninae Stangerochampsa† Albertochampsa† Brachychampsa† Protocaiman† Gnatusuchus† Globidentosuchus† Eocaiman† Notocaiman† Kuttanacaiman† Purussaurus† Mourasuchus† crown group caimans Necrosuchus† Tsoabichi† Paleosuchus trigonatus Smooth-fronted caiman Paleosuchus palpebrosus Cuvier's dwarf caiman Centenariosuchus† Caiman latirostris Broad-snouted caiman Melanosuchus niger Black caiman Caiman yacare Yacare caiman Caiman crocodilus Spectacled caiman Caiman brevirostris† La Venta Caiman† Caiman wannlangstoni† (stem-based group)

(crown group)

The Late Cretaceous taxa Stangerochampsa, Brachychampsa and Albertochampsa have been previously referred to as stem-group caimans,^[5][6] but Walter et al. (2022) recovered them as the basalmost alligatorines based on phylogenetic analysis and claimed that the earliest definitive stem-group caimans are known from the earliest Paleocene.^[7]

References

1. 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.
2. 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.
3. Erickson, Bruce R. (1972). "Albertochampsa langstoni, gen. et sp. nov. A new Alligator from the Cretaceous of Alberta". Scientific Publications of the Science Museum of Minnesota. new series. 2 (1): 1–13.
4. Wu, Xiao-Chun (2005). "Crocodylians". In Currie, Phillip J.; Koppelhus, Eva (eds.). Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Bloomington: Indiana University Press. pp. 277–291. ISBN 0-253-34595-2.
5. 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.
6. 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.
7. 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.