A new ape from Türkiye and the radiation of late Miocene hominines

Building better biochronology: New fossils and 40Ar/39Ar radioisotopic dates from Central Anatolia

Türkiye's geographic position between Europe, Asia, and Africa gives it pivotal importance for understanding the local, interregional, and intercontinental dynamics of Neogene vertebrate evolution. Although rich in vertebrate fossil deposits spanning the Middle and Late Miocene, associated geochronology has been limited by the lack of available volcanic materials that allow radioisotopic dating and geochemical correlation. As a result, calibrating mammalian evolution has been largely restricted to the semicircular application of paleomagnetic inferences combined with temporally ill-constrained and geographically remote biochronological deductions. For example, fossils from three Greek localities and one Anatolian locality assigned to the primate genus Ouranopithecus lack datable samples, leaving its ages poorly constrained. Chronological calibration based on the 40Ar/39Ar results reported here demonstrates how a fauna-focused, precision geochronology can enhance a better understanding of evolving species lineages and the ecosystems they comprise.

An ape partial postcranial skeleton (KNM-NP 64631) from the Middle Miocene of Napudet, northern Kenya

An ape partial postcranial skeleton (KNM-NP 64631) was recovered during the 2015-2021 field seasons at Napudet, a Middle Miocene (∼13 Ma) locality in northern Kenya. Bony elements representing the shoulder, elbow, hip, and ankle joints, thoracic and lumbar vertebral column, and hands and feet, offer valuable new information about the body plan and positional behaviors of Middle Miocene apes. Body mass estimates from femoral head dimensions suggest that the KNM-NP 64631 individual was smaller-bodied (c. 13-17 kg) than some Miocene taxa from eastern Africa, including Ekembo nyanzae, and probably Equatorius africanus or Kenyapithecus wickeri, and was more comparable to smaller-bodied male Nacholapithecus kerioi individuals. Similar to many Miocene apes, the KNM-NP 64631 individual had hip and hallucal tarsometatarsal joints reflecting habitual hindlimb loading in a variety of postures, a distal tibia with a large medial malleolus, an inflated humeral capitulum, probably a long lumbar spine, and a long pollical proximal phalanx relative to femoral head dimensions. The KNM-NP 64631 individual departs from most Early Miocene apes in its possession of a more steeply beveled radial head and deeper humeral zona conoidea, reflecting enhanced supinating-pronating abilities at the humeroradial joint. The KNM-NP 64631 individual also differs from Early Miocene Ekembo heseloni in having a larger elbow joint (inferred from radial head size) relative to the mediolateral width of the lumbar vertebral bodies and a more asymmetrical talar trochlea, and in these ways recalls inferred joint proportions for, and talocrural morphology of, N. kerioi. Compared to most Early Miocene apes, the KNM-NP 64631 individual likely relied on more forelimb-dominated arboreal behaviors, perhaps including vertical climbing (e.g., extended elbow, hoisting). Moreover, the Napudet ape partial postcranial skeleton suggests that an arboreally adapted body plan characterized by relatively large (here, based on joint size) forelimbs, but lacking orthograde suspensory adaptations, may not have been 'unusual' among Middle Miocene apes.

Buronius manfredschmidi-A new small hominid from the early late Miocene of Hammerschmiede (Bavaria, Germany)

The known diversity of European middle and late Miocene hominids has increased significantly during the last decades. Most of these great apes were frugivores in the broadest sense, ranging from soft fruit frugivores most like chimpanzees to hard/tough object feeders like orangutans, varying in size from larger than siamangs (over 17 kg) to larger than most chimpanzees (~60-70 kg). In contrast to the frequent sympatry of hominoids in the early-to-middle Miocene of Africa, in no European Miocene locality more than one hominid taxon has been identified. Here we describe the first case of hominid sympatry in Europe from the 11.62 Ma old Hammerschmiede HAM 5 level, best known from its excellent record of Danuvius guggenmosi. The new fossils are consistent in size with larger pliopithecoids but differ morphologically from any pliopithecoid and from Danuvius. They are also distinguished from early and middle Miocene apes, share affinities with late Miocene apes, and represent a small hitherto unknown late Miocene ape Buronius manfredschmidi. With an estimated body mass of about 10 kg it represents the smallest known hominid taxon. The relative enamel thickness of Buronius is thin and contrasts with Danuvius, whose enamel is twice as thick. The differences between Buronius and Danuvius in tooth and patellar morphology, enamel thickness and body mass are indicative of differing adaptations in each, permitting resource partitioning, in which Buronius was a more folivorous climber.