This study provides a complete morphological description and functional analysis of the carpal bones of the endemic pygmy hippopotamus Phanourios minor, derived from the Upper Pleistocene site of Ayia Napa. From this deposit, numerous skeletal remains of this fossil hippo have been collected, making the locality one of the richest in Cyprus. The carpal bones were compared with those of extant hippopotamuses, to determine the changes that occurred in the fossil hippo. Examination of the elements showed that Phanourios presented some important features that were common among the endemic fossil ungulates of the Mediterranean islands. The carpal bones display a proximal-distal compression due to shortening of the distal part of the leg, due to the new ecological island conditions. However, they are robust with rough areas for strong muscular and ligament insertions, providing stability to the carpal joints, and low speed movement to the animal. The great flexor capabilities, and the limitation in ulnar deviation of the carpus, indicate that P. minor had increased agility in the sagittal plane and restricted transverse movements, while the suggestion of a more unguligrade stance for the species is ambiguous. Thus, the endemic Cypriot hippos developed specialized locomotion, suitable for walking on the rugged terrain of Cyprus, which seems to be different from that of its extant counterparts.

We studied the functional morphology of the postcranial skeleton of the endemic hippopotamus Phanourios minor, derived from the Upper Pleistocene site of Ayia Napa. The deposit, which consists of a hard limestone substrate on which the species moved, has yielded a great abundance of hippopotamus material, making the Ayia Napa locality one of the most important paleontological sites in Cyprus. The immigration of the large‐sized mainland Hippopotamus to Cyprus led to the emergence of a new insular species with its main characteristic being the extremely reduced body size. In this study, all the hindlimb elements of the Cypriot hippo are described in detail and compared with those of the modern species, with the extant Hippopotamus amphibius being considered similar to the possible ancestor of P. minor. In some cases, the morphological comparison is reinforced using bones of other extinct insular and mainland hippos. Additionally, we provided a functional analysis of the hindlimb joints, suggesting specific locomotor habits for the species. The anatomical examination reveals that the elements in P. minor are robust with marked muscular insertion areas resembling those found in Hippopotamus. However, there are also similarities with Choeropsis liberiensis in certain morphofunctional traits. P. minor adapted to slow but powerful locomotion with remarkable stabilization, particularly in the zeugopodium and the autopodium. The knee was less mobile in the craniocaudal direction compared with that in recent hippos, while the abduction–adduction movements of the thigh were advanced. The pes presented good mobility in the sagittal plane and limitation in transversal movements. Thus, P. minor displayed modifications to its limbs, influenced by the mountainous island environment and the body size reduction, resulting in specialized locomotion, which was different from that of extant hippopotamuses.

The bony labyrinth, as part of the inner structure of the petrosal bone, contains the sensory organs of balance and hearing. The semicircular canals, as part of the vestibular apparatus of the inner ear, are involved in the detection of angular motion of the head for maintaining balance and guiding locomotor behavior. While the overall structure of the bony labyrinth is inaccessible embedded in the petrosal bone, high resolution computed tomography makes the study of these structures possible. The purpose of this study is to visualize and precisely quantify the complex inner ear structures of the insular mammal Palaeoloxodon tiliensis and comment on the relationship of these morphologies to the agility and hearing frequency ranges. This study focuses on imaging the shape of the bony labyrinth as well as the semicircular canals, of three petrosal bones, using micro-computed tomography (micro-CT). Shape and size analysis of the cochlea allow for an assessment of morphological differences between species. Specifically, measuring the dimensions of inner ear components as well as the angular distances can express the variation in their balancing abilities and the frequencies of their auditory perception. The morphological characteristics obtained through micro-CT lead to the conclusion that P. tiliensis retained similar conditions to that of its larger relatives, and it was an animal that had hearing in the low frequency ranges.

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