Preliminary observations on the bone microstructure, growth patterns, and life habits of some Triassic temnospondyls from India

Abstract

ABSTRACT-The osteohistology including bone cross-sectional geometry of skeletal elements such as the limb bones, ribs, and intercentra of three Triassic temnospondyl taxa from India were examined to reveal varied bone microstructure and differing growth patterns. The Early Triassic trematosaurid examined is characterized by a change in tissue type from a wellvascularized fibrolamellar bone early in ontogeny to peripheral lamellar bone and lines of arrested growth later in ontogeny, suggesting a fast initial growth followed by a slow and intermittent growth later in life. In contrast, the Middle Triassic paracyclotosaurid and the Late Triassic chigutisaurid examined had a cyclical, overall slow growth, as evidenced from predominance of lamellar bone in the cortex. It is hypothesized that the rapid growth of the trematosaurids was an attempt to stabilize the ecosystem after the Permo-Triassic extinction event. Fibrolamellar bone tissue is described for the first time in a Triassic temnospondyl. Bone cross-sectional geometry, low-to-average cortical porosity, and other parameters imply that the members of the Early and Middle Triassic taxa recovered from India retained a high level of terrestriality. The high cortical porosity and extensive medullary spongiosa suggest that the Late Triassic chigutisaurids had a semi-aquatic or aquatic life style. The varying cortical thickness of the limb bones in paracyclotosaurids may be attributed to different biomechanical constraints.

Cranial bone histology ofMetoposaurus krasiejowensis(Amphibia, Temnospondyli) from the Late Triassic of Poland

“…This also applies in temnospondyls (Damiani, 2000; Steyer et al, 2004; Ray, Mukherjee & Bandyopadhyay, 2009; Mukherjee, Ray & Sengupta, 2010; Sanchez et al, 2010a; Sanchez et al, 2010b; Konietzko-Meier & Klein, 2013; Konietzko-Meier & Sander, 2013; Konietzko-Meier & Schmitt, 2013; Sanchez & Schoch, 2013; Konietzko-Meier, Danto & Gądek, 2014). In the long bones, the three main types of growth marks are known: fast growing zones, more slowly deposited annuli, and Lines of Arrested Growth (LAG-s) that indicate the cessation of the growth (Francillon-Vieillot et al, 1990).…”

Histological skeletochronology indicates developmental plasticity in the early Permian stem lissamphibian Doleserpeton annectens

“…The long‐bone histology of D. annectens has been previously examined (e.g., Castanet, Francillon‐Vieillot, de Ricqlés, & Zylberberg, ), but this is the first skeletochronological study across a broad range of sizes (and inferred semaphoronts). More broadly, the long bones of temnospondyls have been previously studied to identify patterns of growth at the histological level (e.g., de Ricqlés, ; McHugh, , ; Mukherjee, Ray, & Sengupta, ; Sanchez, de Ricqlès, Schoch, & Steyer, ; Sanchez & Schoch, ; Sanchez, Steyer, Schoch, & de Ricqlès, ), but the few studies involving relatively large sample sizes with reconstructed growth series have focused primarily on large‐bodied, aquatic stereospondyls (Konietzko‐Meier & Klein, ; Konietzko‐Meier & Sander, ; Steyer, Laurin, Castanet, & de Ricqlès, ).…”

Temnospondyli bite club: ecomorphological patterns of the most diverse group of early tetrapods

“…Trematosaurs were secondarily aquatic temnospondyls (Warren, 2000) and previous studies (Cosgriff, 1984; Welles, 1993) noted that these animals were deltaic and estuarine piscivores. Recent histological observations demonstrated that at least some members of the family Trematosauridae retained a high degree of terrestriality (Mukherjee et al. , 2010).…”

“…The results for the different cases characterize them as having the strongest skull forms of the analysed temnospondyls. As in the case of trematosaurs, capitosaurs were secondarily aquatic temnospondyls that retained a high degree of terrestriality (Mukherjee et al. , 2010; but see Canoville & Laurin, 2010 for a discussion).…”