Euthalattosuchia, Young, Mark T., Wilberg, Eric W., Johnson, Michela M., Herrera, Yanina, Brandalise, Marco de Andrade, Brignon, Arnaud, Sachs, Sven, Abel, Pascal, Foffa, Davide, Fernández, Marta S., Vignaud, Patrick, Cowgill, Thomas & Brusatte, Stephen L., 2024

Young, Mark T., Wilberg, Eric W., Johnson, Michela M., Herrera, Yanina, Brandalise, Marco de Andrade, Brignon, Arnaud, Sachs, Sven, Abel, Pascal, Foffa, Davide, Fernández, Marta S., Vignaud, Patrick, Cowgill, Thomas & Brusatte, Stephen L., 2024, The history, systematics, and nomenclature of Thalattosuchia (Archosauria: Crocodylomorpha), Zoological Journal of the Linnean Society 200 (2), pp. 547-617 : 597-598

Euthalattosuchia , new clade name (PhyloCode)

RegNum registration number 1016.

Etymology

‘True sea crocodiles’. Eu - is the Neo-Latinized form of the Greek (εὖ, eû), meaning good or true. Thalatto - is from the classical Ancient Greek (θᾰ́λᾰ́ττᾰ́, thálatta) for sea. Suchus is the Neo-Latinized form of the Greek Soukhos (σοῦΧος), which appears to have been the name of an individual tamed crocodile that lived in Arsinoite nome, in Ancient Egypt ( Larcher 1844: 286). The suffix - suchus is today used to refer to crocodiles, crocodylian relatives, or crocodylian analogues. The Neo-Latin suffix - ia denotes an abstract noun of feminine grammatical gender.

Geological range

Middle Jurassic (latest Aalenian or early Bajocian) to Early Cretaceous (earliest Aptian) ( Chiarenza et al. 2015, Wilberg 2015a, Sachs et al. 2020).

PhyloCode phylogenetic definition

The smallest clade within Metriorhynchoidea containing Zoneait nargorum Wilberg 2015a and Thalattosuchus superciliosus (Blainville in Eudes-Deslongchamps 1852).

Reference phylogeny

Fig. 3 .

PhyloCode diagnostic apomorphies

Metriorhynchoid crocodylomorphs with the following unique combination of characters (11): absence of external ornamentation on the lacrimal (20.1); antorbital cavity is open posteriorly and contiguous with the orbital cavity (51.1); middle-posterior regions of the antorbital cavities are greatly expanded compared to the nasopharyngeal ducts (52.1); nasopharyngeal ducts are conspicuously deepened dorsoventrally (57.1); lacrimal vertically oriented and only exposed in lateral view (164.1); fossa present anterior to the orbits, on the lacrimals and prefrontals, with most of the bony surface anterior to the orbit concave (179.2); prefrontal dorsal surface is greatly expanded laterally, overhanging part of the orbit (205.2); ectopterygoid does not contact the maxilla (393.0); extreme enlargement of the cerebral carotid canal foramina, such that they are more than twice as large as any other foramina on the occipital surface (428.2); ulna less than 50% of humerus length (752.4); distal diaphysis of the ulna is flattened (763.1).

Composition

Zoneait and Metriorhynchidae .

Comments

Authorship: This is a new nomen.

Prior phylogenetic definition: This clade has never been phylogenetically defined.

Discussion: We chose not to use Acutirostres Jaekel, 1910 as the nomen for this clade, as Acutirostres has been used prior to 1910 to refer to birds. Unfortunately, the taxa united under Acutirostres differs between authors (see: De-Carlini 1888: 47; Morgana 1903: 28). Moreover, Jaekel (1910) used Acutirostres to unite his Metriorhynchidae and Geosauridae , making it in a synonym of Metriorhynchidae herein.As such, we do not recommend Acutirostres being used in thalattosuchian nomenclature.

The establishment of Euthalattosuchia is our attempt to honour the intended composition of Thalattosuchia sensu Fraas (1901 , 1902). Fraas was clear that his three ‘familien’, Metriorhynchus , Geosaurus , and Dacosaurus [sic] composed his Thalattosuchia , and that the group was fully aquatic. As the nomen Metriorhynchidae is used for that clade, we created Euthalattosuchia for a clade of metriorhynchoids that had both cranial and postcranial adaptations for an aquatic lifestyle (see: Wilberg 2015a).

Figures

Figure 3. The equal weights, no constraints strict consensus topology (C0). Length = 4164, CI = 0.303, RI = 0.831, RC = 0.251, HI = 0.697, number of most parsimonious cladograms hit the hold limit.Phylogeny pruned to highlight Thalattosuchia (see Supporting Information, Appendix S2, Fig. S1 for the entire topology). A, Crocodylomorpha; B, Crocodyliformes; C, Thalattosuchia; D, Neothalattosuchia; E, Teleosauridae; F, Teleosaurinae; G, Aeolodontini; H, Machimosauridae; I, Machimosaurinae; J, Machimosaurini; K, Euthalattosuchia; L, Metriorhynchidae; M, Metriorhynchinae; N, Rhacheosaurini; O, Geosaurinae; P, Geosaurini. Green lines highlight non-neothalattosuchian thalattosuchians, orange lines highlight teleosauroid thalattosuchians, and blue lines highlight metriorhynchoid thalattosuchians.Images from PhyloPics.org, with the teleosauroid by Scott Hartman, and the metriorhynchid by Dmitry Bogdanov (vectorized by T. Michael Keesey), the only change made was to their colouration, and their license is: https://creativecommons.org/licenses/by/3.0/.