A Giant Eocene Whale from Ukraine Uncovers Early Cetacean Adaptations to the Fully Aquatic Life

Davydenko, Svitozar; Shevchenko, T. V.; Ryabokon, T.S.; Tretiakov, R.A.; Gol’din, Pavel

doi:10.1007/s11692-020-09524-8

Cited by 4 publications

(7 citation statements)

References 37 publications

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“…These genera and their morphological similarity were reviewed by Gingerich, Amane and Zouhri (2022). However, due to the fragmentary nature of the specimens and, most likely, homoplasy in postcranial traits shared by cetaceans of this morphotype (Davydenko et al, 2021), the conclusions of that revision are still debated and pending phylogenetic analysis. Meanwhile postcranial anatomy of this morphotype is highly unusual for cetaceans, and only several forms from the Miocene of Paratethys (baleen whales of the family Cetotheriidae and the toothed whale Pachyacanthus) developed similar structures in their postcranial skeleton (Gol'din et al, 2014a;Dewaele et al, 2022).…”

Section: Open Access Edited Bymentioning

confidence: 99%

Diverse bone microanatomy in cetaceans from the Eocene of Ukraine further documents early adaptations to fully aquatic lifestyle

2023

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Basilosauridae, fully aquatic archaeocetes from the Eocene, had osteosclerotic or pachyosteosclerotic structure of ribs and, sometimes, other bones. Such a structure is far different from osteoporotic-like bones of modern cetaceans. A microanatomical and histological study was conducted on axial and limb skeleton of several basilosaurid specimens assigned to the genus Basilotritus, from Bartonian (late middle Eocene) deposits of Ukraine, remarkable for its pachyostotic bones. The postcranial skeleton of these specimens is a complex mosaic of diverse types of bone structure, which include pachyosteosclerotic, osteosclerotic and cancellous elements. The vertebrae have a pachyostotic layered cortex reaching its greatest thickness in the lumbar region. This cortex was strongly vascularized, and its layered structure is due to concentric circles mostly made by longitudinal vascular canals, in addition to cyclical growth lines. Heavy bones are concentrated in the dorsal and ventral areas. Swollen distal ends of thoracic ribs are interpreted as serving as ballast in the ventral area, as also previously proposed for Basilosaurus cetoides. Cortical bone tissue in vertebrae and ribs showed signs of intensive resorption and remodeling. This indicates the use of the axial skeleton not only for buoyancy control but also possibly for calcium and phosphorus recycling.

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Section: Open Access Edited Bymentioning

confidence: 99%

Diverse bone microanatomy in cetaceans from the Eocene of Ukraine further documents early adaptations to fully aquatic lifestyle

2023

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“…einori to that of Sirenia. Recently Davydenko et al [ 55 ] restudied and reinterpreted TSNU-GM 2638, which they regarded as unidentifiable to genus or species, labeling the specimen “Basilosauridae incertae sedis.” Davydenko et al identified some of the vertebrae as lumbars. Their descriptions and illustrations indicate that TSNU-GM 2638 is poorly preserved—raising doubt about its perceived distinction from P .…”

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confidence: 99%

“…Vertebrae described by Gritsenko [ 41 ] are weathered and so poorly illustrated as to be uninterpretable. This was remedied to some extent by Gol’din and Zvonok [ 50 ] and Davydenko et al [ 55 ], who showed that vertebrae Gritsenko interpreted as caudals are really lumbars with anteroposteriorly elongated transverse processes. Uhen and Berndt [ 44 ] described a premolar and a lumbar vertebra with an elongated centrum, anteroposteriorly elongated transverse processes, and pockmarked bone.…”

Section: Systematic Paleontologymentioning

confidence: 99%

“…Gritsenko compared the pachyostosis of P. einori to that of Sirenia. Recently Davydenko et al [55] restudied and reinterpreted TSNU-GM 2638, which they regarded as unidentifiable to genus or species, labeling the specimen "Basilosauridae incertae sedis." Davydenko et al identified some of the vertebrae as lumbars.…”

Section: Plos Onementioning

confidence: 99%

“…Most vertebrae are lumbars (L), but MMGD NsT-90 and NMNH-P OF-2096 are posterior thoracics (T). � Measurements and interpretations of vertebrae described by Gritsenko[41] follow Davydenko et al[55].https://doi.org/10.1371/journal.pone.0276110.t006…”

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Skull and partial skeleton of a new pachycetine genus (Cetacea, Basilosauridae) from the Aridal Formation, Bartonian middle Eocene, of southwestern Morocco

Gingerich

Amane²,

Zouhri³

2022

PLoS ONE

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Pachycetus paulsonii, Pachycetus wardii, and Antaecetus aithai are middle Eocene archaeocete whales found in Europe, North America, and Africa, respectively. The three are placed in the new basilosaurid subfamily Pachycetinae. Antaecetus is a new genus known from Egypt and Morocco, and the only pachycetine known from a substantial postcranial skeleton. The skull of A. aithai described here resembles that of Saghacetus osiris in size, but lacks the narrowly constricted rostrum of Saghacetus. Antaecetus is smaller than Pachycetus and its teeth are more gracile. Upper premolars differ in having two rather than three accessory cusps flanking the principal cusp. Pachycetines differ from dorudontines in having elongated posterior thoracic and lumbar vertebrae like those of Basilosaurus, but differ from basilosaurines and from dorudontines in having conspicuously pachyosteosclerotic vertebrae with dense and thickly laminated cortical bone surrounding a cancellous core. Pachycetinae are also distinctive in having transverse processes on lumbar vertebrae nearly as long anteroposteriorly as the corresponding centrum. We infer from their pachyosteosclerotic vertebrae that pachycetines were probably sirenian-like slow swimmers living in shallow coastal seas and feeding on passing fish and mobile invertebrates.

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A cetacean limb from the Middle Eocene of Ukraine sheds light on mammalian adaptations to life in water

Davydenko,

Solyanik,

Tretiakov

et al. 2023

Biological Journal of the Linnean Society

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There are a few mammalian lineages secondarily adapted to life in water throughout their evolutionary history. Of them, only sirenians and cetaceans evolved as fully aquatic organisms. This transition was accompanied by changes in swimming mode, from foot paddling to tail-powered propulsion, with the forelimbs acting as efficient hydrofoils and the gradual loss of external hindlimbs. Here, we describe an isolated limb from the Middle Eocene of Ukraine, 43–42 Mya, identified as a hindlimb of a fully aquatic cetacean and being the earliest cetacean reported from Europe. It is represented by flattened, jointly articulated bones, identified as the tibia and fibula with a partly reduced knee joint and loose connection to the pes, and by flattened phalanges. This anatomy reveals a hitherto only presumed cetacean morphotype, showing that some of the early fully aquatic cetaceans were four-legged animals with functional hindlimbs that could be involved in advanced styles of swimming. They used either body undulation or lift-based propulsion powered by the tail or feet and could also use a transitional swimming style combining these modes.

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A Giant Eocene Whale from Ukraine Uncovers Early Cetacean Adaptations to the Fully Aquatic Life

Cited by 4 publications

References 37 publications

Diverse bone microanatomy in cetaceans from the Eocene of Ukraine further documents early adaptations to fully aquatic lifestyle

Diverse bone microanatomy in cetaceans from the Eocene of Ukraine further documents early adaptations to fully aquatic lifestyle

Skull and partial skeleton of a new pachycetine genus (Cetacea, Basilosauridae) from the Aridal Formation, Bartonian middle Eocene, of southwestern Morocco

A cetacean limb from the Middle Eocene of Ukraine sheds light on mammalian adaptations to life in water

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