Histology of Dvinosaurus campbelli (Temnospondyli, Dvinosauria) from the Late Permian Locality Gorokhovets, Vladimir Reg
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ology of Dvinosaurus campbelli (Temnospondyli, Dvinosauria) from the Late Permian Locality Gorokhovets, Vladimir Region A. V. Uliakhina, b, *, P. P. Skutschasc, **, and P. G. Saburovc, *** a
bBorissiak
Moscow State University, Moscow, 119992 Russia Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia c St. Petersburg State University, St. Petersburg, 199034 Russia *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected]
Received January 24, 2020; revised February 3, 2020; accepted February 3, 2020
Abstract—This study describes the microanatomical and histological structure of the femur and hypocentra of the neotenic temnospondyl amphibian Dvinosaurus campbelli from the Late Permian locality Gorokhovets, Vladimir Region (Upper Vyatkian Substage, subzone Chroniosuchus paradoxus of the Scutosaurus karpinskii zone). The femur of D. campbelli is characterized by a “pachyosteous” structure (dense thick periosteal cortex in the diaphysis) and a large number of growth marks (about 57); the hypocentrum has an “osteoporotic” structure. The neotenic nature of D. campbelli is confirmed by the presence of unresorbed cartilage in the skeletal elements of large-sized forms. Microanatomical and morphological features indicate that D. campbelli was an ambush feeder (using concealment during hunting). Keywords: Temnospondyli, Dvinosaurus, neoteny, histology, Severodvinian, Upper Permian, Gorokhovets, Eastern Europe DOI: 10.1134/S0031030120060106
INTRODUCTION Dvinosaurian temnospondyls (Dvinosauria) of the genus Dvinosaurus were medium-sized (skull length up to 27 cm) neotenic amphibians that existed in the area of today’s Eastern Europe at the end of the Permian (Ivakhnenko et al., 1997; Schoch, 2013). Their remains have been confidently identified from 45 localities. Dvinosaurus first appears in the fossil record at the beginning of the Late Permian, as indicated by fossils from the Sundyr 1 locality (Lower Putyatin Regional Substage of the Upper Severodvinian Substage; Mari El Republic; Golubev, Bulanov, 2018). The latest representatives are known from the terminal Permian deposits of the Vyatkian Stage, where the genus is represented by two species: D. egregius is known from the localities Bykovka, Sokovka and Metallist in the vicinities of the town of Vyazniki of the Vladimir Region (Shishkin, 1973; Ivakhnenko et al., 1997; Shishkin et al., 2018), while D. purlensis is known from the Purly 2 locality of the Nizhny Novgorod Region (Kalandadze et al., 1968; Gubin, 2004). The morphology of the skull and the postcranial skeleton has been well described, and similarities and differences between individual species have been recognized (Amalitskii, 1921; Sushkin, 1936; Shishkin, 1973; Gubin, 2004). Many questions regarding
individual development and paleoecology of Dvinosaurus, however, remain poorly studied. In this study, in order to reconstruct the growth patterns and other biological characteristics of Dvinosaurus, we analyzed the histology of bony tissue of D. campbelli
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