Comparative postcranial osteohistology and bone histovariability of aquatic and terrestrial turtles: the case of the South American Phrynops hilarii, Hydromedusa tectifera (Pleurodira, Chelidae), and Chelonoidis chilensis (Cryptodira, Testudinidae)

Abstract

This article presents a detailed comparative analysis of the bone microstructure of three extant species of South American turtles. The main histological characteristics of postcranial bones are identified, as well as the intraskeletal, ontogenetic and interspecific variation between aquatic and terrestrial species. For this purpose, thin sections of postcranial bones (seventh cervical vertebra, coracoid, scapula, humerus, radius, ulna, ischium, ilium, pubis, femur, tibia, and fibula) of juvenile and adult specimens of aquatic (Phrynops hilarii and Hydromedusa tectifera) and terrestrial (Chelonoidis chilensis) turtles were analyzed. Bone histology revealed an intraskeletal variation of the microanatomical and microstructural organization in these turtles. The cortical bone is composed of poorly vascularized lamellar and parallel‐fibered bone tissue interrupted with lines of arrested growth (LAGs), reflecting a cyclical slow growth rate throughout these turtles' life. Although in the adult specimens a growth rate decrease was observed, none of them have reached somatic maturity. The juvenile and the adult of Chelonoidis chilensis, unlike the aquatic species studied, presented a higher vascularization in their bones, which could imply a faster growth rate in this land specie. The number of LAGs was higher in the stylopodial and zeugopodial bones, which would make these elements suitable for approximate age estimations. Pectoral and pelvic girdle bones also exhibited a good record of LAGs. The information here obtained on extant species represents a powerful tool for the interpretation of paleobiological traits present in closely related fossil forms.

Ontogenetic and interelemental study of appendicular bones of Caiman latirostris Daudin, 1802 sheds light on osteohistological variability in crocodylians

“…mississippiensis, Chabreck & Joanen, 1979;Horner et al, 2001;Padian et al, 2004;Rainwater et al, 2021;Reid, 1997aReid, , 1997bde Ricqlès et al, 2003;Roberts et al, 1988;Tumarkin-Deratzian, 2007;Werning, 2013;Woodward et al, 2014; Crocodylus sp., Enlow, 1969 Chinsamy, 1991). Some of these earlier studies also reported a concentric arrangement of the LVCs in other reptiles (e.g., Botha & Botha, 2019;Navarro et al, 2023;Pellegrini et al, 2021;Pereyra, 2022;Werning, 2013). In C. latirostris, we also observed radially organized vascular canals in specific bones (e.g., scapula of MLPR-6822 and tibia of MLPR-6809).…”

New findings on the evolution of turtles: A symposium in honor of Marcelo S. de la Fuente

“…The authors digitally dissected 3D models from micro‐CT scans of 70 extant species and observed 51 morphological characters, some with high systematic value. Comparative osteohistological anatomy of aquatic and terrestrial turtles is provided by Pereyra (2023). The bone histology described by Pereyra (2023) reveals that there is intraskeletal variation of the microanatomical and microstructural organization in the analyzed turtles providing valuable data about their paleobiology.…”

“…Comparative osteohistological anatomy of aquatic and terrestrial turtles is provided by Pereyra (2023). The bone histology described by Pereyra (2023) reveals that there is intraskeletal variation of the microanatomical and microstructural organization in the analyzed turtles providing valuable data about their paleobiology. Krahl and Werneburg (2023) use anatomical network analyses to explore the flipper in marine turtles and other amniotes secondarily adapted to the marine environment.…”

Bone histology of Neogene angulate tortoises (Testudines: Testudinidae) from South Africa: palaeobiological and skeletochronological implications

“…Some appear randomly or stacked together within the compacta, and special growth marks are deposited at the time of hatching in reptiles [39], and at the time of birth in mammals (neonatal line) (sensu [92]). Indeed, often certain bones in a single skeleton, such as the stylopodium (humerus, femur) and zeugopodium (fibula, tibia, radius andulna), retain better growth mark record than the bones of cervical vertebrae, and in some cases, variation is noticed at different ontogenetic levels [62]. However, Bhat et al [48] reported that the tibia retains better growth mark record in angulate tortoises.…”

“…[52]). Moreover, although histological studies on chelonian limb bones and/or shell bones have been used to determine skeletochronology and reconstruct growth rates of the testudines [48,49,[53][54][55][56][57][58][59][60][61][62], histological data from a single species, involving both modern and fossilized individuals is non-existent. Here, we fill this gap by investigating the bone histology of Chersina angulata from the Miocene to present, to assess whether their growth dynamics and life-history patterns changed over the past 5 million years.…”