Eusuchia

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Eusuchia
Temporal range:
Ma
Three species of living eusuchian: gharial (left), American alligator (center), and American crocodile (right).
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Crocodylomorpha
Clade: Crocodyliformes
Clade: Neosuchia
Clade: Eusuchia
Huxley, 1875
Subgroups

Eusuchia is a

neosuchian crocodylomorphs that first appeared in the Early Cretaceous, which includes modern crocodilians.[3] Along with Dyrosauridae and Sebecosuchia, they were the only crocodyliformes who survived the K-Pg extinction
.

Definition

Eusuchia was originally defined by

basal eusuchians or non-eusuchian neosuchians is a matter of debate over which definition is used for the group. At least one genus, Isisfordia
, would qualify as a eusuchian under Huxley's definition of the group but would not necessarily qualify under Brochu's definition.

Description

Unlike primitive crocodylomorphs, crocodyliforms have secondary bony palates. This feature enables living crocodylians to safely breathe in through their nostrils while the rest of the head (including the mouth) remains submerged. This structure reaches its greatest elaboration among eusuchians, in which the internal

nares are completely surrounded by the pterygoid bones
.

Unlike more basal neosuchians, eusuchians have four rather than two rows of dorsal armour plates, which are square in shape, with 2 to 4 rows of accessory plates.[5]

Phylogeny

A 2018

stratigraphic data recovered the cladogram below:[2]

A 2021 Rio & Mannion

phylogenetic study using a heavily modified morphological data set recovered the cladogram below:[6]

Bernissartia fagesii
†

Isisfordia duncani
†

Theriosuchus pusillus
†

Paralligatoridae

Shamosuchus djadochtaensis
†

Glen Rose Form

Wannchampsus kirpachi
†

Eusuchia
Hylaeochampsidae†

Acynodon iberoccitanus

Hylaeochampsa vectiana

Iharkutosuchus makadii

References

  1. PMID 22303441. Open access icon
  2. ^
    PMID 30051855
    .
  3. ISBN 0-632-05614-2
    .
  4. doi:10.1146/annurev.earth.31.100901.141308
    .
  5. ISSN 0024-4082
    .
  6. PMID 34567843
    .
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