Acynodon

Acynodon Temporal range: Santonian - Maastrichtian, 86–68  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Skull of Acynodon iberoccitanus (ACAP-FXl)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Archosauria
Clade:	Pseudosuchia
Clade:	Crocodylomorpha
Clade:	Crocodyliformes
Clade:	Metasuchia
Clade:	Neosuchia
Clade:	Eusuchia
Genus:	† Acynodon Buscalioni et al., 1997
Species
†A. iberoccitanusBuscalioni et al., 1997 (type) †A. adriaticusDelfino et al., 2008 †A. lopeziBuscalioni et al., 1997

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

Classification

The genus Acynodon contains three species: A. iberoccitanus, A. adriaticus, and A. lopezi. Fossils have been found in France, Spain, Italy, and Romania, dating back to the Santonian and Maastrichtian periods of the Late Cretaceous. ^[1]

When first described in 1997, it was placed within the family Alligatoridae. ^[2] New findings a decade later led to it being reclassified as a basal globidontan. ^{[3] [1]} Recent studies have since resolved Acynodon as a basal eusuchian crocodylomorph, outside of the Crocodylia crown group, and a close relative to Hylaeochampsa . ^{[4] [5] [6]}

Description

The skull of Acynodon is extremely brevirostrine; it had a very short and broad snout compared to other known alligatorids. ^[3] Its dentition was quite derived, with enlarged molariform teeth and a lack of maxillary and dentary caniniform teeth, presumably an adaptation to feed on slow prey with hard shells. ^[1] The paravertebral osteoderms of Acynodon were distinctively double-keeled.

A. adriaticus was highly specialized to durophagy, likely in shallow, densely vegetated waters. It had an acute lateral snout profile of A. adriaticus in comparison to the more rounded shape of A. iberoccitanus. ^[7]

References

1. Delfino, M.; Martin, J. E.; Buffetaut, E. (2008). "A new species of Acynodon (Crocodylia) from the Upper Cretaceous (Santonian-Campanian) of Villaggio del Pescatore, Italy". Palaeontology . 51 (5): 1091–1106. Bibcode:2008Palgy..51.1091D. doi: 10.1111/j.1475-4983.2008.00800.x .
2. Buscalioni, A. D.; Ortega, F. L.; Vasse, D. (1997). "New crocodiles (Eusuchia: Alligatoroidea) from the Upper Cretaceous of southern Europe". Comptes Rendus de l'Académie des Sciences, Série IIA. 325 (7): 525–530. Bibcode:1997CRASE.325..525B. doi:10.1016/s1251-8050(97)89872-2.
3. Martin, J. E. (2007). "New material of the Late Cretaceous globidontan Acynodon iberoccitanus (crocodylia) from Southern France". Journal of Vertebrate Paleontology . 27 (2): 362–372. doi:10.1671/0272-4634(2007)27[362:NMOTLC]2.0.CO;2. S2CID   130433177.
4. 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.
5. 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.
6. Blanco, A. (2021). "Importance of the postcranial skeleton in eusuchian phylogeny: Reassessing the systematics of allodaposuchid crocodylians". PLOS ONE. 16 (6): e0251900. Bibcode:2021PLoSO..1651900B. doi: 10.1371/journal.pone.0251900 . PMC   8189472 . PMID   34106925.
7. Muscioni, Marco; Chiarenza, Alfio Alessandro; Fernandez, Diego Bladimir Haro; Dreossi, Diego; Bacchia, Flavio; Fanti, Federico (2024-09-12). "Cranial anatomy of Acynodon adriaticus and extreme durophagous adaptations in Eusuchia (Reptilia: Crocodylomorpha)". The Anatomical Record. doi: 10.1002/ar.25574 . ISSN   1932-8486.