Gilchristosuchus
Encyclopedia
Gilchristosuchus is an extinct genus
of neosuchia
n crocodyliform. Its fossil
s have been found in the upper Milk River Formation
of Alberta
, Canada
, in rocks of either latest Santonian
or earliest Campanian
age (Late Cretaceous
). Gilchristosuchus was described in 1993 by Wu and Brinkman. The type species is G. palatinus, in reference to its distinctive palatine
bones.
Gilchristosuchus is based on
RTMP
91.101.1, a partial posterior skull
and a neck vertebra. The skull would have been about 15 centimetres (5.9 in) long when complete. It represents the first articulated crocodylomorph specimen from the Milk River Formation. Isolated remains had been found earlier and assigned to Brachychampsa
and Leidyosuchus
; some of these fossils probably belong to Gichristosuchus. Although the specimen is not large, the ornamentation of the skull surfaces and bone fusion indicate it was an adult. Based on previous research, Wu and Brinkman suggested that their new genus was the most derived neosuchian that wasn't within Eusuchia
, the group including all living crocodilia
ns.
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 neosuchia
Neosuchia
Neosuchia is an unranked 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 than to Notosuchus terrestris...
n crocodyliform. Its fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s have been found in the upper Milk River Formation
Milk River Formation
The Milk River Formation is a near- shore to terrestrial sedimentary unit deposited during the Late Cretaceous in southern Alberta...
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...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, in rocks of either latest Santonian
Santonian
The Santonian is an age in the geologic timescale or a chronostratigraphic stage. It is a subdivision of the Late Cretaceous epoch or Upper Cretaceous series. It spans the time between 85.8 ± 0.7 mya and 83.5 ± 0.7 mya...
or earliest 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 ...
age (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...
). Gilchristosuchus was described in 1993 by Wu and Brinkman. The type species is G. palatinus, in reference to its distinctive palatine
Palatine bone
The palatine bone is a bone in many species of the animal kingdom, commonly termed the palatum .-Human anatomy:...
bones.
Gilchristosuchus 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....
91.101.1, a partial posterior skull
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
and a neck vertebra. The skull would have been about 15 centimetres (5.9 in) long when complete. It represents the first articulated crocodylomorph specimen from the Milk River Formation. Isolated remains had been found earlier and assigned 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 Leidyosuchus
Leidyosuchus
Leidyosuchus is an extinct genus of alligatoroid from the Late Cretaceous of Alberta. It was named in 1907 by Lawrence Lambe, and the type species is L. canadensis. It is known from a number of specimens from the middle Campanian age Dinosaur Park Formation...
; some of these fossils probably belong to Gichristosuchus. Although the specimen is not large, the ornamentation of the skull surfaces and bone fusion indicate it was an adult. Based on previous research, Wu and Brinkman suggested that their new genus was the most derived neosuchian that wasn't within Eusuchia
Eusuchia
Eusuchia is a clade of crocodylomorphs that first appears in the Early Cretaceous with Hylaeochampsa. All living crocodilian species are eusuchians, as are many extinct forms.-Description:...
, the group including all living crocodilia
Crocodilia
Crocodilia is an order of large reptiles that appeared about 84 million years ago in the late Cretaceous Period . They are the closest living relatives of birds, as the two groups are the only known survivors of the Archosauria...
ns.