Surviving in a predator-free environment: Hints from a bone remodelling process in a dwarf Pleistocene deer from Crete

Abstract

a b s t r a c tIslands have been regarded by scientists as a living laboratory of evolution, and a prime target for the study of forces influencing evolution. This research aims to investigate whether a dwarf deer (Candiacervus ropalophorus), that suffered a traumatic fracture of its metatarsal, might have survived, despite the broken limb, in the Cretan free-predator environment for a time longer than commonly expected on mainland. The metatarsal shows a healed complete and oblique fracture at level of the distal part of the diaphysis. Both macroscopic and X-ray examinations show the impressive new bone formation that occurred in the post-trauma period. The size of osseous callus, covering the fracture line and the surface next to the lesion, suggests that the deer has survived several months after the traumatic injury. In a mainland context, an injured deer would hardly have survived for such a long period, because any movement constantly irritated the fracture, dramatically reducing performance or willingness to move and the gait speed, and hampering any escape. Mots clés : CandiacervusCerf nain Fracture osseuse Crète Pléistocène r é s u m é Les îles ont été considérées comme des laboratoires vivants de la biodiversité et une cible pour l'étude des forces qui influent sur l'évolution. Cette recherche vise à déterminer si un cerf nain du Pléistocène de Crète (Candiacervus ropalophorus) qui a subi une fracture de son métatarsien aurait pu survivre, en dépit de sa jambe cassée, dans un environnement sans prédateurs pour un temps plus long que prévu sur le continent. L'os métatarsien montre une fracture complète et oblique au niveau de la diaphyse. Les examens macroscopiques et aux rayons X montrent l'impressionnante formation d'os nouveau qui s'est produite dans la période post-traumatique. La taille de ce cal osseux, couvrant la ligne de fracture, suggère que le cerf a survécu durant plusieurs mois au traumatisme, même si tout mouvement

The intriguing giant deer from the Bate cave (Crete): could paleohistological evidence question its taxonomy and nomenclature?

“…The bone tissue types have been described following the classification proposed by Francillon-Vieillot et al (1990). The same protocol and histomorphometric procedures were followed in order to compare morphological and histomorphological features of the C. ropalophorus metatarsal bone (Palombo & Zedda 2016).…”

“…2015a,b; Bartosiewicz 2016, 2018; Lyras et al . 2016, 2019; Palombo & Zedda 2016; Olivier et al . 2017; Veitschegger 2017; Orlandi‐Oliveras et al .…”

“…During the last couple of decades, studies in the fields of paleohistology and paleopathology have been Palombo & Zedda 2016;Olivier et al 2017;Veitschegger 2017;Orlandi-Oliveras et al 2018;Veitschegger et al 2018;Zoboli et al 2018;Labarca & Pacheco 2019;Miszkiewicz et al 2019;Woolley et al 2019;de Souza Barbosa et al 2020;Xing et al 2020;Zedda et al 2020). Interesting results about the growth rate and the seasonality of death are also achieved by the histological approach (Castanet et al 2004;Sander & Andrassy 2006;Köhler & Moyà-Solà 2009;Köhler et al 2012;Kolb et al 2015a).…”

Bone lesions in a Late Pleistocene assemblage of the insular deer Candiacervus sp.II from Liko cave (Crete, Greece)

“…There are many important studies on the phylogeny, anatomy, life history, and development of insular ungulates ( Van der Geer et al, 2010, an overview). However, studies of their palaeopathology are few (Maempel, 1993;Waldren, 1999;Jordana and Kohler, 2011;Palombo and Zedda, 2016). The study of ungulate bone lesions and their interpretation may help our understanding of island ecosystems, as well as elucidate life histories and behavior of extinct animals (Rothschild and Martin, 1993).…”

Causal explanations for the evolution of ‘low gear’ locomotion in insular ruminants

“…Furthermore, there would not be any downside in the consequent loss of cursorial aptitude in the focal taxa, due to the lack of mammalian predators that generally characterizes insular faunas (Sondaar, 1977). Lack of predators may select for increasing body stability, while decreasing running speed and manoeuvrability (Lyras, Giannakopoulou, Lillis, Veis, & Papadopoulos, 2016; Palombo & Zedda, 2016; Van der Geer et al., 2011).…”