Metriorhynchoidea Fitzinger, 1843

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 : 596-597

Metriorhynchoidea Fitzinger, 1843 (Zoological Code)

Metriorhynchoidea Deraniyagala 1939: 308, converted clade name (PhyloCode)

RegNum registration number 1015.

Type genus: Metriorhynchus von Meyer, 1832 .

Etymology

‘Those resembling Metriorhynchus ’. The stem Metriorhynch - is based on the genus Metriorhynchus . - oidea, is a Neo-Latin plural suffix for resembling. Under Article 29.2 of the Zoological Code, the suffix - oidea denotes a superfamily rank within the family-group.

Geological range

Early Jurassic (early Toarcian) to Early Cretaceous (earliest Aptian) ( Buffetaut 1980, Chiarenza et al. 2015, Sachs et al. 2020). Given that teleosauroids appear to extend into the ‘Hettangian– Sinemurian’ (see: Hicham et al. 2023), we cannot preclude that the geological range of Metriorhynchoidea is far older than we currently know.

PhyloCode phylogenetic definition

The largest clade within Thalattosuchia containing Metriorhynchus brevirostris ( Holl 1829) but not Teleosaurus cadomensis ( Lamouroux 1820) and Macrospondylus bollensis ( Jäger 1828) .

Reference phylogeny

Fig. 3 .

Zoological Code diagnosis and PhyloCode diagnostic apomorphies

Thalattosuchian crocodylomorphs with the following unique combination of characters (21): tooth row and occipital condyle aligned in the same horizontal plane (shared with the unnamed Chinese teleosauroid and Charitomenosuchus leedsi ) (3.1); expansion of the posterior nasal cavity creating concave depressions on the internal surface of the prefrontals (41.1– 3); presence of a sulcus anterior to the antorbital/preorbital cavity (172.1); frontal minimum interorbital width greater than, or equal to, the width of one supratemporal fossa and the intertemporal bar (reversals in Opisuchus , Geosaurinae , and within Cricosaurus and Maledictosuchus ) (233.0); presence of a scleral ring within the orbits (286.1); jugal beneath the orbit rod-like (270.0); extensive participation of the prefrontal in the orbit anterior margin (reversal in Teleidosaurus ) (277.1); maxilla–palatine suture ‘M’-shaped (364.2); within the trigeminal fossa, the foramina are ‘bilobate’/hour-glass shaped, with an anterior projection of the proötic slightly dividing into dorsal (for rostral middle cerebral vein) and ventral (for exit of trigeminal branches) portions (441.0); dentary does not reach posterior to the orbit (shared with Machimosaurus ) (509.0); dentary tooth opposite the premaxilla–maxilla suture not enlarged (reversal in Geosaurus giganteus ) (632.0); axis dichocephalous (724.1); coracoid with fan-shaped distal and proximal ends (741.2); ulna clearly shorter than the humerus (shared with Gavialis , Congosaurus , Pietraroiasuchus , and Aeolodon ) (752.3–4); supraacetabular crest is poorly developed (793.1); hindlimbs (femur + tibia + metatarsal III) under 50% of trunk (presacral vertebrae minus the atlas-axis) length (shared with machimosaurine machimosaurids and aeolodontin teleosaurids) (807.4–5); femur posteromedial tuber the largest of the proximal tubera (815.2); metatarsals subequal, or shorter, in length compared to their respective digit phalanges (831.1–2); metatarsal I proximal end enlarged (832.1–3); pes digit IV is longer than digit III (833.1); absence of ventral tail osteoderms (shared with Pietraroiasuchus ) (862.1).

Composition

The early diverging taxa Pelagosaurus , Teleidosaurus , Magyarosuchus , Opisuchus , Eoneustes , and Zoneait , and the subclade Metriorhynchidae .

Comments

Authorship: The nomen Metriorhynchoidea was first used by Deraniyagala (1939). However, he explicitly referred to Metriorhynchoidea as a suborder, and not as a family-group nomen (as one would expect given the suffix). The first to use Metriorhynchoidea as a family-group nomen in a published article was Frey et al. (2002). However, under the Zoological Code Fitzinger 1843 is the nominal authority. The nominal author of a family-group is the author who first erected a family-group taxon that is valid (in fulfilment of Article 11), and in accordance with the Zoological Code Principle of Coordination applied to family-group names (Article 36.1). Under the PhyloCode, Deraniyagala (1939) is the nominal authority.

Prior phylogenetic definition: Young and Andrade (2009) defined Metriorhynchoidea as the most inclusive clade consisting of Metriorhynchus geoffroyii von Meyer, 1832 but not Teleosaurus cadomensis ( Lamouroux 1820) . Here we added the external specifier Macrospondylus bollensis , to ensure both Teleosauridae and Machimosauridae are explicitly excluded from Metriorhynchoidea .

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/.