Fossil Record 24(2): 357-377, doi: 10.5194/fr-24-357-2021
Ontogenetic development of the European basal aquatic turtle Pleurosternon bullockii (Paracryptodira, Pleurosternidae)
expand article infoAndrea Guerrero, Adán Pérez-García§
‡ Universidad Nacional de Educación a Distancia, Spain§ Grupo de Biología Evolutiva, Facultad de Ciencias, UNED, Paseo de la Senda del Rey 9, 28040 Madrid, Spain
Open Access

Several British specimens of relatively complete and partialshells of small pleurosternid turtles, found in the Purbeck Limestone Group(Berriasian, Lower Cretaceous), are analysed in detail here. Despite havingbeen found more than a century ago, most of them remained unpublished untilnow. Due to the scarce knowledge available to date about the smallindividuals of Pleurosternidae from the British record, their taxonomicstatus was doubtful. Thus, some authors proposed their attribution to a newbut not defined taxon of small size, whereas others suggested that theycould represent juvenile individuals of Pleurosternon bullockii, the adults of which were alsofound in the Purbeck Limestone Group but at different levels. Knowledgeabout the shell of the adult individuals of Pleurosternon bullockii has notably increased recently,abundant information on its intraspecific variability being currentlyavailable. In this context, a detailed study of the small specimens throughqualitative and quantitative approaches is performed here. The resultsare evidence a significant range of shape variability because of ontogeneticdevelopment, as well as other types of intraspecific variation such asinter-individual variation. As a consequence, their attribution to juvenileindividuals of Pleurosternon bullockii is justified, providing new data on the ontogeneticdevelopment of a basal form.