Stangerochampsa
Encyclopedia
Stangerochampsa is an extinct genus
of globidonta
n alligatoroid
, possibly an alligatorine
, 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 20.03 centimetres (7.9 in) long from the tip of the snout to the occipital condyle
, and is 13 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.
, found their new genus to be closest to Brachychampsa
, and then Albertochampsa
and Hylaeochampsa
successively, as part of a clade
within Alligatorinae that also included Allognathosuchus
, Ceratosuchus
, and Wannaganosuchus
. This arrangement also unites most Mesozoic
and Paleogene
alligatorines. Brochu (1999), in an analysis of all alligatoroids, found Stangerochampsa and Brachychampsa to be just outside of Alligatoridae, and suggested that Stangerochampsa and Albertochampsa were synonymous. Brochu (2004) and Hill and Lucas (2006) also found Stangerochampsa to be outside of Alligatorinae; Hill and Lucas found Albertochampsa to its sister taxon.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of globidonta
Globidonta
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...
n alligatoroid
Alligatoroidea
Alligatoroidea is a superfamily of crocodilians that evolved in the Late Cretaceous period. Cladistically, it is defined as Alligator mississippiensis and all crocodylians more closely related to A. mississippiensis than to either Crocodylus niloticus or Gavialis gangeticus ....
, possibly an alligatorine
Alligatorinae
Alligatorinae are one of two subfamilies of the family Alligatoridae.-Taxonomy:* Subfamily Alligatorinae** Genus Chrysochampsa ** Genus Hassiacosuchus ** Genus Navajosuchus ** Genus Ceratosuchus...
, from the Late Cretaceous
Late Cretaceous
The Late Cretaceous is the younger of two epochs into which the Cretaceous period is divided in the geologic timescale. Rock strata from this epoch form the Upper Cretaceous series...
of Alberta
Alberta
Alberta is a province of Canada. It had an estimated population of 3.7 million in 2010 making it the most populous of Canada's three prairie provinces...
. It is based on
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
RTMP
Royal Tyrrell Museum of Palaeontology
The Royal Tyrrell Museum is a popular Canadian tourist attraction and a leading centre of palaeontological research noted for its collection of more than 130,000 fossils....
.86.61.1, a skull, partial lower jaws, and partial postcranial skeleton discovered in the late Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...
–early Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...
-age Horseshoe Canyon Formation
Horseshoe Canyon Formation
The Horseshoe Canyon Formation is part of the Edmonton Group and is up to 230m in thickness. It is Late Campanian to Early Maastrichtian in age and is composed of mudstone, sandstone, and carbonaceous shales...
. Stangerochampsa was described in 1996 by Wu and colleagues. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the 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 20.03 centimetres (7.9 in) long from the tip of the snout to the occipital condyle
Occipital condyle
The occipital condyles are undersurface facets of the occipital bone in vertebrates, which function in articulation with the superior facets of the atlas vertebra....
, and is 13 centimetres (5.1 in) wide at its greatest, while the thigh bone
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
is 14.2 centimetres (5.6 in) long. It had heterodont
Heterodont
The anatomical term heterodont refers to animals which possess more than a single tooth morphology. For example, members of the Synapsida generally possess incisors, canines , premolars, and molars. The presence of heterodont dentition is evidence of some degree of feeding/hunting specialization...
dentition, with large crushing teeth at the rear of the jaws.
Classification
Wu and colleagues, using phylogenetic analysesCladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
, found their new genus to be closest to Brachychampsa
Brachychampsa
Brachychampsa is an extinct genus of alligatoroid. Specimens have been found from New Mexico, Colorado, Wyoming, Montana, North and South Dakota, New Jersey, and Saskatchewan. One specimen has been found from the Darbasa Formation of Kazakhstan, although the species status is indeterminant for the...
, and then Albertochampsa
Albertochampsa
Albertochampsa is an extinct genus of globidontan alligatoroid 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...
and Hylaeochampsa
Hylaeochampsa
Hylaeochampsa is an extinct genus of eusuchian crocodylomorph. It is known only from a partial skull recovered from Barremian-age rocks of the Lower Cretaceous Vectis Formation of the Isle of Wight. This skull, BMNH R 177, is short and wide, with a eusuchian-like palate and inferred enlarged...
successively, as part of a clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
within Alligatorinae that also included Allognathosuchus
Allognathosuchus
Allognathosuchus is an extinct genus of alligatorine crocodylian with a complicated taxonomic history. This small alligatorine is known for its stout jaws and bulbous teeth, found near the rear of the tooth row in upper and lower jaws. These adaptations have historically been interpreted as...
, Ceratosuchus
Ceratosuchus
Ceratosuchus is an extinct genus of alligatorine 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...
, and Wannaganosuchus
Wannaganosuchus
Wannaganosuchus is an extinct genus of small alligatorid...
. This arrangement also unites most Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
and Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...
alligatorines. Brochu (1999), in an analysis of all alligatoroids, found Stangerochampsa and Brachychampsa to be just outside of Alligatoridae, and suggested that Stangerochampsa and Albertochampsa were synonymous. Brochu (2004) and Hill and Lucas (2006) also found Stangerochampsa to be outside of Alligatorinae; Hill and Lucas found Albertochampsa to its sister taxon.