Hylaeochampsidae is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of basal

eusuchia Eusuchia is a clade of neosuchian Crocodylomorpha, crocodylomorphs that first appeared in the Early Cretaceous, which includes modern Crocodilia, crocodilians. Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survi ...

n crocodylomorphs thought to be closely related to the order Crocodylia.

Classification

Hylaeochampsidae was first constructed by Charles William Andrews in 1913 to include just one member: '' Hylaeochampsa''. However, a new genus named '' Iharkutosuchus'' was described in 2007 and was found to be a sister taxon of ''Hylaeochampsa'', and thus a member of the family Hylaeochampsidae. The genus '' Heterosuchus'', named in 1887, may also be a member of the family. However, it is likely to be synonymous with ''Hylaeochampsa'' and has been considered a ''

nomen dubium In binomial nomenclature, a ''nomen dubium'' (Latin for "doubtful name", plural ''nomina dubia'') is a scientific name that is of unknown or doubtful application. Zoology In case of a ''nomen dubium,'' it may be impossible to determine whether a ...

'' by James M. Clark and Mark Norell. Clark and Norell also claimed that there is no evidence to suggest that the two genera form a true

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

distinct from other eusuchians, because remains associated with ''Heterosuchus'' are to fragmentary to show any clear phylogenetic relationship. A fourth genus called '' Pietraroiasuchus'' was assigned to Hylaeochampsidae in 2011. A phylogenetic analysis conducted with the description of ''Pietraroiasuchus'' also found '' Pachycheilosuchus'' to be part of the family. In this 2011 study, Buscalioni ''et al.''

cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

ally defined Hylaeochampsidae as a node-based clade of the last common ancestor of ''Hylaeochampsa vectiana'', ''Iharkutosuchus makadii'', ''Pachycheilosuchus trinquei'' and ''Pietraroiasuchus ormezzanoi'' and all of its descendants. The

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below results from the 2011 Buscalioni ''et al.'' study:

Distribution and description

The family existed during the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period in what is now

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

and the

Middle East The Middle East (term originally coined in English language) is a geopolitical region encompassing the Arabian Peninsula, the Levant, Turkey, Egypt, Iran, and Iraq. The term came into widespread usage by the United Kingdom and western Eur ...

. ''Hylaeochampsa'' and its possible synonym ''Heterosuchus'' have both been found from the Vectis Formation of the

Isle of Wight The Isle of Wight (Help:IPA/English, /waɪt/ Help:Pronunciation respelling key, ''WYTE'') is an island off the south coast of England which, together with its surrounding uninhabited islets and Skerry, skerries, is also a ceremonial county. T ...

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

, dating back to the Barremian stage of the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

. Specimens of ''Iharkutosuchus'' have been found from the Csehbánya Formation in western

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

, which was deposited during the

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 86.3 ± 0.7 mya ( million years ago) and 83.6 ± 0.7 m ...

stage of the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

. All hylaeochampsids had highly brevirostrine snouts and exhibited heterodonty, with large teeth concentrated posteriorly that were most likely adapted to crushing. In ''Iharkutosuchus'' these teeth were even multicusped. This is often characteristic of

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

s but is highly unusual for a crocodylomorph, and suggests that the animal may have been herbivorous.

References

External links

Hylaeochampsidae
in the Paleobiology Database Early Cretaceous crocodylomorphs Prehistoric reptiles of Europe Late Cretaceous crocodylomorphs Early Cretaceous first appearances Santonian extinctions Pseudosuchian families {{paleo-archosaur-stub