Kostensuchus atrox
- 演化之聲
- Mar 20
- 2 min read
Updated: Apr 9
Age
Cretaceous（Maastrichtian）
66 Ma
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Crocodylomorpha
Family: Peirosauridae
Genus: Kostensuchus
Species: Kostensuchus atrox
Morphological description
Kostensuchus atrox is one of the largest members of Peirosauridae, reaching an estimated body length of approximately 3.5 meters and a body mass of around 250 kilograms.
Its skull is robust, wide, and heavily built, with the snout comprising slightly more than half of the total skull length . A distinct notch is present at the junction between the premaxilla and maxilla, separating their tooth rows; when the jaws are closed, this notch accommodates the enlarged fourth dentary tooth . The teeth exhibit ziphodont morphology, bearing serrated cutting edges adapted for slicing flesh.
The external nares are positioned at the anterior end of the snout and open in an anterolateral direction. The anterior portion of the jaws gradually narrows and rises dorsally, forming a structure that separates the nostrils and connects with the nasal bones.
Etymology
The generic name "Kosten" derives from a word for "wind" in a local Indigenous language, while "suchus" refers to the crocodile-headed Egyptian deity Sobek.
The species name "atrox" comes from Greek, meaning "cruel" .
Biological description
Fossils of Kostensuchus atrox were discovered in Santa Cruz Province, Patagonia, Argentina, within the Maastrichtian Chorrillo Formation, representing the southernmost and youngest known occurrence of Peirosauridae. The holotype specimen (MPM-PV 23554) consists of an articulated skull, jaws, and much of the postcranial skeleton, although parts of the limbs and tail are missing. Despite these absences, it remains one of the most complete and informative peirosaurid specimens currently known.
Phylogenetic analyses place Kostensuchus within a monophyletic group of broad-snouted peirosaurids that originated during the Late Cretaceous. These forms likely evolved from smaller, more generalized ancestors.
Its large body size, broad snout, and serrated teeth indicate a highly specialized predatory lifestyle, capable of capturing and processing large prey. Within its ecosystem, Kostensuchus functioned as a top predator.
The Chorrillo Formation represents a strongly seasonal floodplain environment with relatively poor soils and vegetation dominated by gymnosperms, with angiosperms being comparatively rare. The fauna of this ecosystem was diverse, including ankylosaurs, titanosaurs, ornithopods, birds, and the large megaraptorid theropod Maip, which likely represented another apex predator in the region.
（Author: Bai Leng）
Reference
Novas, F. E., Pol, D., Agnolín, F. L., Carvalho, I. S., Manane, M., Tsuihiji, T., Rozadilla, S., Lio, G. L., Isasi, M. P. (2025). A new large hypercarnivorous crocodyliform from the Maastrichtian of Southern Patagonia, Argentina. PLOS ONE.
-49.9, -72.5
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