PaleoMoz Project: new fossils from Mozambique and South Africa help elucidate the origins of endothermy

The origins of endothermy (warm-bloodedness) have been one of the most challenging problems of paleontology and biology, because there are confounding lines of evidence. Some indications coming from stable isotopic geochemistry point that some dicynodonts (mammal forerunners) were endotherms. We aim to use propagation-phase contrast microtomography from the BM05 beamline to obtain high-quality scans of the skulls of newly found dicynodonts from Mozambique to help elucidating their semicircular canal morphology. Semicircular canal morphology adapted to elevated body temperatures because inner ear endolymph viscosity increases exponentially with temperature. Additionally, the skulls of some basal anomodonts and a gorgonopsian (respectively the consecutive sister groups to dicynodonts) will serve as contrasting endpoints. Our project will also serve as a foundation to support the PhD thesis of the Mozambican student Zanildo Macungo, under the PaleoMoz Project.

恒温性（endothermy）的起源始终是古生物学与生物学领域最具挑战性的课题之一，因其相关证据存在相互矛盾的复杂线索。来自稳定同位素地球化学（stable isotopic geochemistry）的多项研究结果表明，部分二齿兽类（dicynodonts，即哺乳动物的早期祖先）为恒温动物。本研究拟利用BM05光束线（BM05 beamline）的传播相位衬度显微CT（propagation-phase contrast microtomography）技术，对在莫桑比克新发现的二齿兽类头骨开展高质量扫描，以阐明其半规管形态特征。由于内耳内淋巴的粘度随温度呈指数级增长，半规管形态会随体温升高发生适应性演化。此外，部分基干异齿兽类（basal anomodonts）与1件兽头类（gorgonopsian）的头骨将作为对照样本，该两类群分别为二齿兽类的连续姊妹群。本项目同时将作为支撑莫桑比克学生扎尼尔多·马孔戈（Zanildo Macungo）博士学位论文研究的基础，隶属于PaleoMoz项目（PaleoMoz Project）。