Teleosauroidea Geoffroy Saint-Hilaire, 1831 (Zoological Code)

Teleosauroidea Delfino and Dal Sasso 2006: 250 (PhyloCode)

RegNum registration number 801.

Type genus: Teleosaurus Geoffroy Saint-Hilaire, 1825.

Etymology

‘Those resembling Teleosaurus ’. The stem Teleosaur - is based on the genus Teleosaurus. - 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 (Hettangian–Sinemurian) to Early Cretaceous (late Barremian) (Fanti et al. 2016, Cortés et al. 2019, Johnson et al. 2020 a, Young and Sachs 2021, Hicham et al. 2023).

PhyloCode phylogenetic definition

The largest clade within Thalattosuchia containing Teleosaurus cadomensis (Lamouroux 1820) but not Metriorhynchus brevirostris (Holl 1829) (Metriorhynchoidea). Definition from Johnson et al. (2022b).

Reference phylogeny

Fig. 3.

Zoological Code diagnosis and PhyloCode diagnostic apomorphies

Thalattosuchian crocodylomorphs with the following unique combination of characters (13): external and internal antorbital fenestrae are subequal or not distinguishable (169.0); supratemporal fenestrae longer than the orbits (198.2); squamosal does not project further posteriorly than the occipital condyle (reversal in the unnamed Chinese teleosauroid) (249.0); orbits have a dorsal inclination (271.1); in palatal view, the maxilla projects anteriorly with straightened margins creating a sub-rectangular shape (353.2); consistent presence of occipital tuberosities (410.1); within the trigeminal fossa, the foramina are fully divided into two openings by a bridge formed by proötic, dorsal opening interpreted as rostral middle cerebral vein and ventral opening as exit for trigeminal branches (441.1); paired ridges present on the medial ventral surface of the basisphenoid (449.1); main body of the quadrates are strongly inclined (464.2); first and second premaxillary alveoli form a couplet (reversals present within Teleosauridae) (584.1); third dentary tooth occludes against the premaxilla–maxilla suture (635.0); coracoid with a fan-shaped distal end and a triangularshaped proximal end (741.1); scapular blade is less than 1.5 times the width of the scapular shaft (shared with the unnamed Toarcian metriorhynchoid) (744.1).

Composition

Machimosauridae (composed of Macrospondylus and Machimosaurinae, and based on our phylogenetic analyses possibly also the ‘Hettangian–Sinemurian’ teleosauroid from Morocco — Hicham et al. 2023) and Teleosauridae (composed of the unnamed Chinese teleosauroid, Indosinosuchus, Mystriosaurus, Seldsienean, Teleosaurinae, and Aeolodontini).

Comments

Authorship: While the nomen Teleosauroidea was first used by Delfino and Dal Sasso (2006: 250), under the Zoological Code Geoffroy Saint-Hilaire 1831 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). However, under the PhyloCode, Delfino and Dal Sasso (2006) is the nominal authority.

Comments: As demonstrated by Johnson et al. (2018, 2020a, b, c) teleosauroids were far more morphologically diverse than previously thought. The previous use of Steneosaurus as a ‘wastebasket’ to place the majority of teleosauroid species has greatly held back our understanding of the clade. For example, the diversity shown in Figure 21 would have been placed in the genus Steneosaurus prior to the work of Johnson et al. (2018, 2020a). Even though some species are more closely related to the genera Teleosaurus and Platysuchus (Mystriosaurus and Mycterosuchus; Fig. 21A, B) and others are more closely related to Machimosaurus (Macrospondylus, Charitomenosuchus, and particularly Lemmysuchus; Fig. 21C–E). Based on the phylogenetic analyses presented herein (Figs 3–12), the only way to render Steneosaurus monophyletic would be to place all thalattosuchians more derived than Turnersuchus into the genus Steneosaurus (as Plagiophthalmosuchus gracilirostris, originally named Steneosaurus gracilirostris, is recovered outside of Neothalattosuchia).The only other way to use the genus Steneosaurus as ‘traditionally’ defined would be to accept it is as a paraphyletic taxon (and accept the usage of paraphyletic taxa), one in which the other traditionally accepted teleosauroid genera (Teleosaurus, Platysuchus, and Machimosaurus) and Metriorhynchoidea, evolved from. That would place Neothalattosuchia, Teleosauroidea, Teleosauridae, Aeolodontini, Machimosauridae, Machimosaurinae, and Machimosaurini, as subclades within Steneosaurus. Such an action would subsume a remarkable level of morphological variation into a paraphyletic genus, creating a genus that could never be morphologically defined, only defined by what it is not. Having such a genus would allow for fragmentary specimens to be a generic assignment, as argued for by Hua et al. (2021). But that begs the question, what does the designation Steneosaurus sp. mean when the genus is paraphyletic, and to such a degree? Although Hua et al. (2021) consider the lack of a generic assignment to be a weakness of the Johnson et al. (2020a) systematization, we argue it is in fact a strength. Assignments such as Teleosauroidea indeterminate, or Machimosauridae indet., show the limits of our current knowledge and gives a clear indication where in the teleosauroid tree we think a specimen belongs. Using a paraphyletic Steneosaurus (or any other genus, like Metriorhynchus — Le Mort et al. 2022) merely provides the illusion of specificity.

of braincase pneumaticity in thalattosuchians, and the enlargement of the internal vascular canals. For details on the computed tomography scans and internal descriptions, see: Brusatte et al. 2016; Herrera et al. 2018; Cowgill et al. 2023. Abbreviations: II, cranial nerve II; IV, cranial nerve IV; V, cranial nerve V; IX, cranial nerve IX; X–XI, cranial nerves X–XI; XII, cranial nerve XII; bsd, basisphenoid diverticulum of the media pharyngeal sinus; cc, cerebral carotid canal; dvs, transverse dural venous sinus; en, dural envelope endocast; pts, paratympanic sinus; cqc, cranioquadrate canal; ifd, infundibular diverticulum of the paratympanic sinus; qud, quadrate diverticulum of the paratympanic sinus; itd, intertympanic diverticulum of the paratympanic sinus; el, endosseous labyrinth; mpt, median pharyngeal sinus; oa, orbital artery canals; otd, otoccipital diverticulum of the paratympanic sinus; pf, pituitary fossa cavity; ptt, paratympanic tube; tov, temporoorbital vessel canals.

Hicham et al. (2023) described a specimen from the Hettangian or Sinemurian of Morocco that is remarkably similar to early Toarcian teleosauroids (Johnson et al. 2020a). Two characters from our diagnosis support their placement of the specimen within Teleosauroidea: (i) in palatal view, the maxilla projects anteriorly with straightened margins creating a sub-rectangular shape, and (ii) first and second premaxillary alveoli form a couplet. Moreover, in our phylogenetic analyses the specimen is recovered within Teleosauroidea, specifically in Machimosauridae. We regard the referral of the specimen to Machimosauridae to be premature, however, as many of the diagnostic characters for Teleosauridae and Machimosauridae cannot be scored for that specimen. While our understanding of thalattosuchian character distribution prior to the Toarcian is currently limited, at present we concur with Hicham et al. (2023) that the Morocco specimen is a teleosauroid. Thus, extending the geological range of the clade by possibly 15 million years or more.