Three‐dimensional CT examination of the forefoot and hindfoot of the hippopotamus and tapir during a semiaquatic walking

Endo, Hideki; Yoshida, Misaki; Nguyen, Truong Son; Akiba, Yuki; Takeda, Masahiro; Kudo, Kazutoshi

doi:10.1111/ahe.12405

Cited by 9 publications

(12 citation statements)

References 9 publications

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“…Preservations of most hair and nail keratins in hippos is consistent with the fact that unlike cetaceans, hippos have prominent keratinized hoofs [94] and distinct pelage and vibrissa hairs, albeit only in restricted anatomical sites. Particularly, brush-like hairs on hippo tail aid in spreading feces upon defecation, a behavior used by both river hippo and pygmy hippo for territorial marking [95].…”

Section: Comparison Of Inactivated Skin Genes and Epidermal Phenotypesupporting

confidence: 77%

Genomic and anatomical comparisons of skin support independent adaptation to life in water by cetaceans and hippos

Springer¹,

Guerrero‐Juarez²,

Huelsmann

et al. 2020

Preprint

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SUMMARYThe macroevolutionary transition from terra firma to obligatory inhabitance of the marine hydrosphere has occurred twice in the history of Mammalia: Cetacea and Sirenia. In the case of Cetacea (whales, dolphins, porpoises), molecular phylogenies provide unambiguous evidence that fully aquatic cetaceans and semiaquatic hippopotamids (hippos) are each other’s closest living relatives. Ancestral reconstructions further suggest that some adaptations to the aquatic realm evolved in the common ancestor of Cetancodonta (Cetacea+Hippopotamidae). An alternative hypothesis is that these adaptations evolved independently in cetaceans and hippos. Here, we focus on the integumentary system and evaluate these hypotheses by integrating new histological data for cetaceans and hippos, the first genome-scale data for pygmy hippopotamus, and comprehensive genomic screens and molecular evolutionary analyses for protein-coding genes that have been inactivated in hippos and cetaceans. We identified ten skin-related genes that are inactivated in both cetaceans and hippos, including genes that are related to sebaceous glands, hair follicles, and epidermal differentiation. However, none of these genes exhibit inactivating mutations that are shared by cetaceans and hippos. Mean dates for the inactivation of skin genes in these two clades serve as proxies for phenotypic changes and suggest that hair reduction/loss, the loss of sebaceous glands, and changes to the keratinization program occurred ~16 million years earlier in cetaceans (~46.5 Ma) than in hippos (~30.5 Ma). These results, together with histological differences in the integument and prior analyses of oxygen isotopes from stem hippopotamids (“anthracotheres”), support the hypothesis that aquatic adaptations evolved independently in hippos and cetaceans.

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Section: Comparison Of Inactivated Skin Genes and Epidermal Phenotypesupporting

confidence: 77%

Genomic and anatomical comparisons of skin support independent adaptation to life in water by cetaceans and hippos

Springer¹,

Guerrero‐Juarez²,

Huelsmann

et al. 2020

Preprint

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“…They consist of limited studies on the skeleton of Hippopotamus amphibius (Gratiolet 1867) and fossil taxa (Kowalesky 1873;Scott and Jepsen 1940;Dineur 1981;Pickford 2008), and on detailed descriptions of the forelimb and hind limb myology of Choeropsis liberiensis and H. amphibius, respectively (Fisher et al 2007;2010). In addition, there are data on swimming and aquatic bottom-walking abilities in H. amphibius (Coughlin et al 2009;Endo et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Paleoecological Inferences from Long Bone Microanatomical Specializations in Hippopotamoidea (Mammalia, Artiodactyla)

Houssaye¹,

Martin

Boisserie

et al. 2021

J Mammal Evol

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HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

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“…In fact, the digits in P. minor could present even closer placement than those in the extant hippos. The more open arrangement is vital for Choeropsis as it must transfer its weight through all digits, to prevent the splaying of the toes during walking on the soft ground (Fisher et al, 2007), or not to stuck to the marshes (Endo et al, 2019), constantly assisted from strong intrinsic muscles. Moreover, an open aspect of the foot is also advantageous for H. amphibius to transmit effectively its large body mass to all digits and gain great underwater mobility (Endo et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Functional morphology of the hindlimb of fossilized pygmy hippopotamus from Ayia Napa (Cyprus)

Georgitsis

Liakopoulou

Θεοδώρου

et al. 2022

Journal of Morphology

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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.

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Three‐dimensional CT examination of the forefoot and hindfoot of the hippopotamus and tapir during a semiaquatic walking

Cited by 9 publications

References 9 publications

Genomic and anatomical comparisons of skin support independent adaptation to life in water by cetaceans and hippos

Genomic and anatomical comparisons of skin support independent adaptation to life in water by cetaceans and hippos

Paleoecological Inferences from Long Bone Microanatomical Specializations in Hippopotamoidea (Mammalia, Artiodactyla)

Functional morphology of the hindlimb of fossilized pygmy hippopotamus from Ayia Napa (Cyprus)

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