Sophineta

Discovery

Sophineta is known from holotype ZPAL RV/175, a nearly complete right maxilla. Many specimens are referred to the species and represent frontals, parietals, prefrontal, postfrontals, postorbitals, jugals, squamosals, pterygoids, quadrates, maxillae, premaxilla, dentaries, vertebrae and ilia. Skull fragments and vertebral column were associated. All specimens are housed in the Institute of Paleobiology, Polish Academy of Sciences, Warsaw. All specimens were discovered in situ and collected by a team from the Institute of Geological Sciences of Jagiellonian University, Kraków (Paszkowski and Wieczorek) in 1982 from the Czatkowice 1 locality. This locality is a single exposure from which a diverse fauna of small vertebrates is known. It comes from karst deposits developed in Early Carboniferous (Turnaisian to Mid Visean) limestone at the Czatkowice quarry near Kraków, Southern Poland. The locality dates to the earliest Late Olenekian stage of the Early Triassic period, about 247.3 million years ago. Sophineta is the smaller of the two lepidosauromorph reptiles known from the Early Triassic karst deposits of Czatkowice quarry, the larger on being the kuehneosaurid Pamelina. The material from Czatkowice 1 was transferred to the Museum of the Earth and Institute of Paleobiology of the Polish Academy of Sciences, Warsaw, were a preliminary chemical preparation in acetic acid was performed. More effective preparation started only in the 1990s and terminated in 2007.

Description

Sophineta differs from all kuehneosaurs and Marmoretta in having short notochordal vertebrae without transverse processes. It also has pleurodont teeth, rather than subthecodont teeth like in all kuehneosaurs. Other differences are the presence of paired rather than confluent nares, the presence of weakly developed zygosphenoidal articulations on the vertebrae, the possession of notochordal rather than amphiplatyan vertebrae, and compressed keeled tooth tips rather than simple cones. It differs from the Paliguana in having a deeper facial process on the maxilla and a much smaller lacrimal and from Marmoretta in that the latter has a specialised maxillary/premaxillary overlap. Sophineta resembles lepidosaurs in having weak zygosphenes, short vertebrae and single−headed ribs throughout the column, but differs in having a shallower pleurodont tooth implantation and the apparent absence of both a thyroid fenestra and functional caudal autotomy. Sophineta had unspecialised vertebral column but fairly derived skull structure, including the tall facial process of the maxilla, reduced lacrimal and pleurodonty. These traits also resemble those of early lepidosaurs rather than stem−lepidosaurs. A reconstruction of the skull of Sophineta revealed a "modified diapsid skull" with a relatively short preorbital region. The orbits, narial openings and upper temporal fenestrae are large, and the lower temporal fenestrae are open ventrally. Based on the dimensions of the ZPAL RV/175 and skull proportions in Marmoretta, its total skull length is estimated to be about 10 mm (0.39 in), with a body length (excludig the tail) of about 30 mm (1.2 in).

Phylogeny

Susan E. Evans and Magdalena Borsuk−Białynicka (2009) performed a phylogenetic analysis that recovered Sophineta as the sister group of Lepidosauria. The inclusion of Sophineta displaced the relictual Middle Jurassic Marmoretta and gave the origin of Lepidosauria much older age. The cladogram below follows their results.

Etymology

Sophineta was first described and named by Susan E. Evans and Magdalena Borsuk−Białynicka in 2009 and the type species is Sophineta cracoviensis. The generic name honors Professor Zofia Kielan-Jaworowska of the Instytut Paleobiologii PAN, and it is derived from Greek sophia, meaning "wisdom" which is the classical root of the name Zofia. The specific name is derived from Cracovia, the Latin name for Kraków, the closest major Polish city to the Czatkowice 1 locality (the type locality of Sophineta). It is also honors researchers at the University of Kraków for their work at the locality.