Variability in premolar and molar root number in a modern population of Pan troglodytes verus

A Computed Tomographic Study of the Molar Teeth of Babyrousa spp

A photographic and computed tomography (CT) scanning study was carried out on 295 molar teeth of 18 adult male Babyrousa babyrussa skulls and 8 skulls of Babyrousa celebensis including seven adult males and one adult female. The occlusal morphology of the permanent maxillary and mandibular molar teeth of B. babyrussa was very similar to that of B. celebensis. Most B. babyrussa maxillary molar teeth had six roots, with small numbers of teeth having four, five or seven roots. A similar pattern was suggested in B. celebensis. Mandibular molar teeth had between four and eight roots. Tooth roots of maxillary and mandibular first and second molar teeth were largely tapering, rod-like structures. The roots of the right and left maxillary third molar teeth had a more complex arrangement; some were inserted almost vertically into the maxilla; others were orientated in a more distal direction. The mesial and distal roots were splayed in appearance. The right and left mandibular third molar tooth roots retained elements of the open 'C' shape and were generally orientated distally. The pulp chambers were arched to fit under the main cusps in all molar teeth. Pulp canals were variable in number.

Antagonistic interaction between Ezh2 and Arid1a coordinates root patterning and development via Cdkn2a in mouse molars

Patterning is a critical step during organogenesis and is closely associated with the physiological function of organs. Tooth root shapes are finely tuned to provide precise occlusal support to facilitate the function of each tooth type. However, the mechanism regulating tooth root patterning and development is largely unknown. In this study, we provide the first in vivo evidence demonstrating that Ezh2 in the dental mesenchyme determines patterning and furcation formation during dental root development in mouse molars. Mechanistically, an antagonistic interaction between epigenetic regulators Ezh2 and Arid1a controls Cdkn2a expression in the dental mesenchyme to regulate dental root patterning and development. These findings indicate the importance of balanced epigenetic regulation in determining the tooth root pattern and the integration of roots with the jaw bones to achieve physiological function. Collectively, our study provides important clues about the regulation of organogenesis and has general implications for tooth regeneration in the future.

Can Pallars i Llobateres: A new hominoid-bearing locality from the late Miocene of the Vallès-Penedès Basin (NE Iberian Peninsula)

In the Iberian Peninsula, Miocene apes (Hominoidea) are generally rare and mostly restricted to the Vallès-Penedès Basin. Here we report a new hominoid maxillary fragment with M² from this basin. It was surface-collected in March 2017 from the site of Can Pallars i Llobateres (CPL, Sant Quirze del Vallès), where fossil apes had not been previously recorded. The locality of provenance (CPL-M), which has delivered no further fossil remains, is located very close (ca. 50 m) to previously known CPL outcrops, and not very far (ca. 500 m in NW direction) from the classical hominoid-bearing locality of Can Poncic 1. Here we describe the new fossil and, based on the size and proportions of the M², justify its taxonomic attribution to Hispanopithecus cf. laietanus, a species previously recorded from several Vallesian sites of the Vallès-Penedès Basin. Based on the associated mammalian fauna from CPL, we also provide a biochronological dating and a paleoenvironmental reconstruction for the site. The associated fauna enables an unambiguous correlation to the Cricetulodon hartenbergeri - Progonomys hispanicus interval local subzone, with an estimated age of 9.98-9.73 Ma (late Vallesian, MN10). Therefore, CPL-M is roughly coeval with the Hispanopithecus laietanus-bearing localities of Can Llobateres 1 and Can Feu 1, and minimally older than those of La Tarumba 1 and Can Llobateres 2. In contrast, CPL-M is younger than the early Vallesian (MN9) localities of Can Poncic 1 (the type locality of Hispanopithecus crusafonti) as well as Polinyà 2 (Gabarró) and Estació Depuradora d'Aigües Residuals-Riu Ripoll 13, where Hispanopithecus sp. is recorded. The associated fauna from CPL indicates a densely forested and humid paleoenvironment with nearby freshwater. This supports the view that Hispanopithecus might have been restricted to dense wetland forests soon before its extinction during the late Vallesian, due to progressive climatic deterioration. Coupled with the existence of other fossiliferous outcrops in the area, this find is most promising for the prospect of discovering additional fossil hominoid remains in the future.

Potential hominin affinities of Graecopithecus from the Late Miocene of Europe

The split of our own clade from the Panini is undocumented in the fossil record. To fill this gap we investigated the dentognathic morphology of Graecopithecus freybergi from Pyrgos Vassilissis (Greece) and cf. Graecopithecus sp. from Azmaka (Bulgaria), using new μCT and 3D reconstructions of the two known specimens. Pyrgos Vassilissis and Azmaka are currently dated to the early Messinian at 7.175 Ma and 7.24 Ma. Mainly based on its external preservation and the previously vague dating, Graecopithecus is often referred to as nomen dubium. The examination of its previously unknown dental root and pulp canal morphology confirms the taxonomic distinction from the significantly older northern Greek hominine Ouranopithecus. Furthermore, it shows features that point to a possible phylogenetic affinity with hominins. G. freybergi uniquely shares p4 partial root fusion and a possible canine root reduction with this tribe and therefore, provides intriguing evidence of what could be the oldest known hominin.