''Wannchampsus'' ("

Wann Langston, Jr. Wann Langston Jr. (1921 – April 7, 2013) was an American paleontologist and professor at the University of Texas at Austin. Langston worked on a number of different reptiles and amphibians in his long career, beginning with the 1950 description ...

's crocodile") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of paralligatorid

neosuchia Neosuchia is a clade within Mesoeucrocodylia that includes all modern extant crocodilians and their closest fossil relatives. It is defined as the most inclusive clade containing all crocodylomorphs more closely related to ''Crocodylus niloticus' ...

n, close to but not a true

crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...

n. It is known from fossils discovered in

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eight ...

rocks in north-central

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, United States.

Description and classification

''Wannchampsus'' is based on SMU 76604, a partial skull and lower jaw. This fossil is attached by matrix to another partial skull of the same genus and species, SMU 76605. A handful of other fossils were found associated, mostly representing forelimbs and

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e. These fossils were found in rocks of the late

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), a ...

-age Lower Cretaceous

Twin Mountains Formation The Twin Mountains Formation, also known as the Twin Mak Formation, is a sedimentary rock formation, within the Trinity Group, found in Texas of the United States of America. It is a terrestrial formation of Aptian age (Lower Cretaceous), and ...

, southwest of Stephenville, in

Comanche County, Texas Comanche County is a county located on the Edwards Plateau in Central Texas. As of the 2020 census, its population was 13,594. The county seat is Comanche. The county was founded in 1856 and is named for the Comanche Native American tribe. Hi ...

; the site is otherwise known as the

Proctor Lake Proctor Lake is a U.S. Army Corps of Engineers reservoir along the Leon River located in Comanche County, Texas, Comanche County in the U.S. state of Texas, around 3 miles (5 km) west of Proctor, Texas. Proctor Lake Dam and the reservoir are ...

dinosaur locality. ''Wannchampsus'' was described in

2014 File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...

by Thomas Adams. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''W. kirpachi'', in honor of Wesley Kirpach, "who was instrumental in the discovery and excavations of the type specimen". Wkirpachi1

The skulls are described as "low and broad", and are small; SMU 76604 is estimated at long, and SMU 76605 is estimated at long. The lower jaw lacks external

mandibular fenestra The skull is a bone protective Cranial cavity, cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible ...

e, and the third tooth of the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

(main tooth-bearing bone of the upper jaw) and the fourth tooth of the

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

(tooth-bearing bone of the lower jaw) are enlarged. The teeth become broader and less conical going back toward the jaw joint, and the teeth at the

anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

end of the lower jaw project forward (the anterior end of the upper jaw, composed of the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...

s, is not known). Features of the skull and vertebrae indicate that the individuals are subadults. Adams performed a

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

and found ''Wannchampsus kirpachi'' to be a

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

paralligatorid, closely related to the " Glen Rose form", which he regarded as belonging to the genus ''Wannchampsus''.

References

Neosuchians Early Cretaceous crocodylomorphs of North America Early Cretaceous reptiles of North America Fossil taxa described in 2014 Paleontology in Texas Prehistoric pseudosuchian genera {{paleo-archosaur-stub