''Wannia'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of basal

phytosaur Phytosaurs (Φυτόσαυροι in greek) are an extinct group of large, mostly semiaquatic Late Triassic archosauriform reptiles. Phytosaurs belong to the order Phytosauria. Phytosauria and Phytosauridae are often considered to be equivalent g ...

reptile known from the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic Epoch. ...

(late

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227 m ...

or early Norian stage) of

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

, southern United States. It contains a single species, ''Wannia scurriensis'', which is known from a single specimen. This species was originally named as a species referred to '' Paleorhinus'' and later was considered as a possible junior synonym of '' Paleorhinus bransoni''. However its re-description revealed five

autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

, and a phylogenetic position as the most basal known phytosaur, justifying the erection of a new generic name for the species.

Discovery and naming

''Wannia'' was first described and named by the late Dr. Wann Langston Jr. in 1949 as a species referable to '' Paleorhinus'', ''P. scurriensis''. An alternative generic name, ''Wannia'', was proposed by Michelle R. Stocker in

2013 File:2013 Events Collage V2.png, From left, clockwise: Edward Snowden becomes internationally famous for leaking classified NSA wiretapping information; Typhoon Haiyan kills over 6,000 in the Philippines and Southeast Asia; The Dhaka garment fa ...

creating the

new combination ''Combinatio nova'', abbreviated ''comb. nov.'' (sometimes ''n. comb.''), is Latin for "new combination". It is used in taxonomic biology literature when a new name is introduced based on a pre-existing name. The term should not to be confused wi ...

''Wannia scurriensis''. The generic name honors Langston for his extensive work on archosaur palaeontology, and the specific name refers to the

Scurry County Scurry County is a county located in the U.S. state of Texas. As of the 2020 census, its population was 16,932. Its county seat is Snyder, which is the home for Western Texas College. Scurry County is named for Confederate General William ...

where the holotype was found. ''Wannia'' is known solely from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

TTU P-00539, a partial

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

preserved in two parts housed at

Texas Tech University Texas Tech University (Texas Tech, Tech, or TTU) is a public research university in Lubbock, Texas. Established on , and called Texas Technological College until 1969, it is the main institution of the five-institution Texas Tech University Sy ...

. TTU P-11422, a partial juvenile skull, had also been referred to ''"P." scurriensis'', however Stocker (2013) found no basis for this referral as the specimens do not share any synapomorphies. The holotype was collected near

Lake Alan Henry Lake Alan Henry is a reservoir situated in the upper Brazos River Basin in the United States. Created by the construction of the John T. Montford Dam in 1993, it is operated and used as a future tertiary water supply by the city of Lubbock, Texas ...

, 4 km northeast of the town of Camp Springs, from the Camp Springs Formation of the

Dockum Group The Dockum is a Late Triassic (approximately late Carnian through Rhaetian, or 223–200 Ma) geologic group found primarily on the Llano Estacado of western Texas and eastern New Mexico with minor exposures in southwestern Kansas, eastern Colora ...

. Previously known as the Camp Springs Conglomerate, this unit probably correlates with the lower member of the Santa Rosa Sandstone in Texas and the Tecololito Member of the Santa Rosa Formation in New Mexico. The age of this unit is not precisely known, it was originally considered to be late

based on correlations with the Opponitzer Limestone of Austria, using the presence of '' Dolerosaurus'', which was previously considered to be a member of ''Paleorhinus''. However, recent

zircon Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is Zr SiO4. An empirical formula showing some of t ...

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares ...

suggests that the Santa Rosa Sandstone is equivalent to the Norian-aged Shinarump Member. Furthermore, the Post Quarry which is within the stratigraphically higher Cooper Canyon Formation of the Dockum Group was recently demonstrated to be mid Norian (220–215 Ma). Thus the most probable age for the Camp Springs Formation and the lower member of the Santa Rosa Sandstone is latest Carnian or early Norian.

Description

Stocker (2013) diagnosed ''Wannia scurriensis'' using five unambiguous

(unique traits) and additionally by a unique combination of characters. Unlike all other phytosaurs, the basitubera, areas at the base of the skull in front of its attachment point with the neck, are widely separated mediolaterally. A distinctive ridge is present on the lateral surface of the

jugal bone The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anato ...

. A thickened shelf is present along the posteroventral edge of an expanded "wing" formed by the

pterygoid bone The pterygoid is a paired bone forming part of the palate of many vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fis ...

and the

quadrate bone The quadrate bone is a skull bone in most tetrapods, including amphibians, sauropsids (reptiles, birds), and early synapsids. In most tetrapods, the quadrate bone connects to the quadratojugal and squamosal bones in the skull, and forms upper pa ...

. A swelling on the nasal bone is present behind the posterior borders of the nares. Finally, the "septomaxillae", probably not homologous to the septomaxillae of

squamate Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 10,900 species, it ...

s and

synapsid Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...

s, do not contact one another and do not form part of the internarial septum. Eight characters are shared by ''Wannia'' and all other phytosaurs ( synapomorphies), including nares that are directed dorsally and the presence of separate ossification, the septomaxilla, anterior to the nasals and surrounded by the

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

. Although a

synonymy A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

between ''Wannia scurriensis'' and '' Paleorhinus bransoni'' was previously suggested, ''Wannia scurriensis'' differs from ''Paleorhinus bransoni'' in lacking a contact between the premaxilla and palatine bone, as seen in '' Paleorhinus angustifrons'' and '' Ebrachosuchus neukami''. Additionally, ''W. scurriensis'' differs from both species of ''Paleorhinus'' in the presence of a ridge, rather than a row of nodes, on the lateral surface of the jugal. The small partial skull previously catalogued as referable to this species, TTU P-11422, does not share any diagnostic characters with the holotype. The specimens can be compared only in the area surrounding the right antorbital fenestra. Although TTU P-11422 does have a large antorbital fossa with a slightly posterodorsally inclined antorbital fenestra as in ''W. scurriensis'', the nasals just posterior to the nares are not swollen in contrast to the autapomorphic condition seen in the latter. However, a further preparation of TTU P-11422 may reveal additional morphological traits.

References

{{Taxonbar, from=Q16760255 Phytosaurs Prehistoric reptile genera Late Triassic reptiles of North America Paleontology in Texas Fossil taxa described in 2013 Taxa named by Michelle R. Stocker