The internal anatomy of titanosaur osteoderms from the Upper Cretaceous of Spain is compatible with a role in oogenesis.
Dermal armor is one of the most intriguing features of some titanosaurs, the only sauropod dinosaurs that bore osteoderms. Some studies have revealed cavities of varying sizes inside some titanosaur osteoderms, interpreted as the result of bone remodeling for mineral mobilization. Several hypotheses have been proposed to explain the need for mineral mobilization in titanosaurs. However, rejecting those hypotheses was difficult with hitherto available evidence. The Upper Cretaceous site of Lo Hueco (Cuenca; Spain) has yielded one of the largest titanosaur osteoderm sets available. Observation of pre-existing breakages in the fossils and CT-scanning have revealed a predominant internal channel network for bulb and root osteoderms: most had a very compact spongy bone core, perfused by large longitudinal branching neurovascular canals. Only few osteoderms from the same bed, which was deposited in a single and short event, had areas with low-density spongy bone. This void-like low-density bone is always associated with internal channels. It is also present in osteoderms of different sizes. This scenario is best explained when considering that Lo Hueco titanosaurs might have used their osteoderms as a source of calcium that was mobilized during oogenesis, although other hypotheses cannot be completely ruled out.
Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain.|Unidad de Paleontología, Universidad Autónoma de Madrid, C/Darwin 2 28049, Madrid, Spain.
Daniel
D
Vidal
Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain.
Francisco
F
Ortega
Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain.
Francisco
F
Gascó
Grupo de Biología Evolutiva, UNED, Paseo Senda del Rey 9, 28040, Madrid, Spain.
Alejandro
A
Serrano-Martínez
Unidad de Paleontología, Universidad Autónoma de Madrid, C/Darwin 2 28049, Madrid, Spain.
José Luis
JL
Sanz
D000818:Animals; D015519:Bone Density; D016723:Bone Remodeling; D001842:Bone and Bones / Q000737:chemistry / Q000000981:diagnostic imaging* / Q000648:ultrastructure; D002118:Calcium / Q000378:metabolism*; D025061:Dinosaurs / Q000033:anatomy & histology* / Q000145:classification / Q000502:physiology; D005260:Female; D005580:Fossils / Q000648:ultrastructure; D008297:Male; D009866:Oogenesis / Q000502:physiology*; D010802:Phylogeny; D013030:Spain; D014057:Tomography, X-Ray Computed
D002118:Calcium