Dawid A. Iurino

New footprints from Laetoli (Tanzania) provide evidence for marked body size variation in early hominins

Laetoli is a well-known palaeontological locality in northern Tanzania whose outstanding record includes the earliest hominin footprints in the world (3.66 million years old), discovered in 1978 at Site G and attributed to Australopithecus afarensis. Here, we report hominin tracks unearthed in the new Site S at Laetoli and referred to two bipedal individuals (S1 and S2) moving on the same palaeosurface and in the same direction as the three hominins documented at Site G. The stature estimates for S1 greatly exceed those previously reconstructed for Au. afarensis from both skeletal material and footprint data. In combination with a comparative reappraisal of the Site G footprints, the evidence collected here embodies very important additions to the Pliocene record of hominin behaviour and morphology. Our results are consistent with considerable body size variation and, probably, degree of sexual dimorphism within a single species of bipedal hominins as early as 3.66 million years ago. DOI: http://dx.doi.org/10.7554/eLife.19568.001

Medical CT scanning and the study of hidden oral pathologies in fossil carnivores

Skeletal pathologies and oral disease are largely unexplored in fossil carnivores. Dental abnormalities, fractures, trauma, supernumerary teeth, tumours, periodontitis, and other bacterial infections are some of the diseases that leave traces on fossilized skulls, but their identification is not always possible by external observation on the specimen. Moreover a large number of pathologies are “hidden”, partially or completely invisible on the external surface of the bones because their development took place within the bones. The degree and the type of fossilization, the state of preservation and the fossil size are just a few other factors that influence the analysis of these structures. Digital scanning techniques are useful to solve such difficulties. X-ray study can provide valuable information on bone and teeth diseases, by allowing the visualization of the internal structure of the fossil bones, without the alteration and/or destruction of the specimen. Many aspects of the life of carnivores are regulated by their health condition, and in particular by the teeth and jaws conditions, individuals with evident disability due to the pathology and injuries are not able to perform properly some basic activities, such as foraging and defence. This paper presents new methods of non-invasive analysis to identify and understand oral pathologies in fossil carnivores. They can be further explored to obtain detailed palaeoecological reconstructions of their mode of life.KurzfassungSkelett-Pathologien und Mundhöhlenerkrankungen bei fossilen Fleischfressern sind größtenteils unerforscht. Zahnanomalien, Frakturen, Traumata, überzählige Zähne, Tumore, Parodontitis und andere bakterielle Infektionen sind nur einige der Krankheiten, die Spuren auf versteinerten Schädeln hinterlassen, aber ihre Identifizierung ist nicht immer durch eine äußere Beobachtung der Probe möglich. Zudem ist eine große Anzahl von Pathologien “versteckt”, teilweise oder vollständig auf der äußeren Oberfläche der Knochen unsichtbar, da sich ihre Entstehung in den Knochen vollzog. Der Grad und die Art der Versteinerung, der Erhaltungszustand und die Größe des Fossils sind nur einige der Faktoren, welche die Analyse dieser Strukturen beeinflussen. Digitale Scan-Techniken sind dabei durchaus nützlich, solche Schwierigkeiten zu lösen. Mithilfe der Röntgenuntersuchung können wertvolle Informationen über Knochen-und Zahnerkrankungen im Inneren des fossilen Knochenaufbaus dargestellt werden, ohne die jeweilige Probe zu beeinträchtigen und/oder zu zerstören. Viele Aspekte des Lebens von Fleischfressern können an ihren gesundheitlichen Zustand festgestellt werden, insbesondere an dem Zahn - und Kieferzustand. Individuen mit einer erwiesenen Behinderung dieser Strukturen aufgrund von Pathologien und Verletzungen sind nicht in der Lage, einige grundlegende Aktivitäten wie Nahrungssuche und Abwehr ordnungsgemäß durchzuführen. Diese Abhandlung erörtert neue Methoden der nicht-invasiven Analyse, um Mundhöhlenerkrankungen bei fossilen Fleischfressern zu identifizieren und zu verstehen. Sie können somit weitergehend untersucht werden, um eine detaillierte paläoökologische Rekonstruktionen ihrer Lebensweise zu erhalten.

Phylogenetic and functional implications of the ear region anatomy of Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina

Several detailed studies of the external morphology of the ear region in extinct sloths have been published in the past few decades, and this anatomical region has proved extremely helpful in elucidating the phylogenetic relationships among the members of this mammalian clade. Few studies of the inner ear anatomy in these peculiar animals were conducted historically, but these are increasing in number in recent years, in both the extinct and extant representatives, due to wider access to CT-scanning facilities, which allow non-destructive access to internal morphologies. In the present study, we analyze the extinct ground sloth Glossotherium robustum and provide a description of the external features of the ear region and the endocranial side of the petrosal bone, coupled with the first data on the anatomy of the bony labyrinth. Some features observable in the ear region of G. robustum (e.g., the shape and size of the entotympanic bone and the morphology of the posteromedial surface of the petrosal) are highly variable, both intraspecifically and intraindividually. The form of the bony labyrinth of G. robustum is also described, providing the first data from this anatomical region for the family Mylodontidae. The anatomy of the bony labyrinth of the genus Glossotherium is here compared at the level of the superorder Xenarthra, including all available extant and extinct representatives, using geometric morphometric methods. In light of the new data, we discuss the evolution of inner ear anatomy in the xenarthran clade, and most particularly in sloths, considering the influence of phylogeny, allometry, and physiology on the shape of this highly informative region of the skull. These analyses show that the inner ear of Glossotherium more closely resembles that of the extant anteaters, and to a lesser extent those of the giant ground sloth Megatherium and euphractine armadillos, than those of the extant sloths Bradypus and Choloepus, further demonstrating the striking morphological convergence between the two extant sloth genera.

Synchrotron radiation reveals the identity of the large felid from Monte Argentario (Early Pleistocene, Italy)

We describe here a partial skull with associated mandible of a large felid from Monte Argentario, Italy (Early Pleistocene; ~1.5 million years). Propagation x-ray phase-contrast synchrotron microtomography of the specimen, still partially embedded in the rock matrix, allows ascribing it reliably to Acinonyx pardinensis, one of the most intriguing extinct carnivorans of the Old World Plio-Pleistocene. The analysis of images and 3D models obtained through synchrotron microtomography – here applied for the first time on a Plio-Pleistocene carnivoran – reveals a mosaic of cheetah-like and Panthera-like features, with the latter justifying previous attributions of the fossil to the extinct Eurasian jaguar Panthera gombaszoegensis. Similarly, we reassign to A. pardinensis some other Italian materials previously referred to P. gombaszoegensis (sites of Pietrafitta and Ellera di Corciano). The recognition of Panthera-like characters in A. pardinensis leads to reconsidering the ecological role of this species, whose hunting strategy was likely to be different from those of the living cheetah. Furthermore, we hypothesise that the high intraspecific variation in body size in A. pardinensis can be the result of sexual dimorphism, as observed today in all large-sized felids.

GROTTA ROMANELLI (SOUTHERN ITALY, APULIA): LEGACIES AND ISSUES IN EXCAVATING A KEY SITE FOR THE PLEISTOCENE OF THE MEDITERRANEAN

Grotta Romanelli, located on the Adriatic coast of southern Apulia (Italy), is considered a key site for the Mediterranean Pleistocene for its archaeological and palaeontological contents. The site, discovered in 1874, was re-evaluated only in 1900, when P. E. Stasi realised that it contained the first evidence of the Palaeolithic in Italy. Starting in 1914, G.A. Blanc led a pioneering excavation campaign, for the first-time using scientific methods applied to systematic paleontological and stratigraphical studies. Blanc proposed a stratigraphic framework for the cave. Different dating methods (C 14 and U/Th) were used to temporally constrain the deposits. The extensive studies of the cave and its contents were mostly published in journals with limited distribution and access, until the end of the 1970s, when the site became forgotten. In 2015, with the permission of the authorities, a new excavation campaign began, led by a team from Sapienza University of Rome in collaboration with IGAG CNR and other research institutions. The research team had to deal with the consequences of more than 40 years of inactivity in the field and the combined effect of erosion and legal, as well as illegal, excavations. In this paper, we provide a database of all the information published during the first 70 years of excavations and highlight the outstanding problems and contradictions between the chronological and geomorphological evidence, the features of the faunal assemblages and the limestone artefacts.

CT scanning analysis of Megantereon whitei (Carnivora, Machairodontinae) from Monte Argentario (Early Pleistocene, central Italy): evidence of atavistic teeth

CT scanning analysis applied to vertebrate palaeontology is providing an increasing number of data of great interest. This method can be used in many branches of palaeontology such as the investigation of all the fossilized elements in a hard matrix and the hidden structures in the bones. A large number of pathologies are “hidden”, completely or partially invisible on the external surface of the bones because their development took place within the bones. However, the study of these diseases and abnormalities plays a crucial role in our understanding of evolutionary and adaptive processes of extinct taxa. The analysis of a partial skeleton of the sabre-toothed felid Megantereon whitei from the Early Pleistocene karst filling deposits of Monte Argentario (Tuscany, Italy) has been carried out. The CT scanning analysis put in evidence the presence of supernumerary teeth (P2) and the absence of P3 in the mandible. The occurrence of P2 can be considered as an evidence of atavism. Such an archaic feature is recorded for the first time in Megantereon.

Digital Cranial Endocasts of the Extinct Sloth Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina: Description and Comparison with the Extant Sloths

The internal cranial morphology of the terrestrial sloth Glossotherium robustum is described here based on a neurocranium from the late Pleistocene of the Pampean region of Buenos Aires, northeastern Argentina. The first published data on the morphology of the brain cavity of this species date back to the latest nineteenth century. The novel techniques of CT scanning and digital reconstructions enable non-destructive access to the internal cranial features of both extinct and extant vertebrates, and thus improve our knowledge of anatomical features that had previously remained obscure. Therefore, we performed CT scans on the posterior half of a skull of G. robustum and created digital models of the endocasts and internal structures. The results reveal the morphology of the brain cavity itself, as well as the paranasal sinuses and the trajectory of several cranial nerves and blood vessels. These features have been compared with the two extant folivoran genera, the two-toed sloth Choloepus and the three-toed sloth Bradypus. For many characteristics, especially those related to the paranasal pneumaticity and the brain cavity, a closer similarity between Glossotherium and Choloepus is observed, in accordance with the most widely accepted phylogenetic scenarios. However, other features are only shared by the two extant genera, but are probably related to allometric effects and the convergence that affected the two modern lineages. This study, which represents the first exhaustive analysis of digital endocasts of a fossil sloth, reveals the importance of the application of new methodologies, such as CT scans, for elucidating the evolutionary history of this peculiar mammalian clade.