A new stem odontocete from the late Oligocene Pysht Formation in Washington State, U.S.A.

Vélez‐Juarbe, Jorge

doi:10.1080/02724634.2017.1366916

Cited by 14 publications

(55 citation statements)

References 35 publications

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“…The phylogenetic position of CCNHM 1000 was reconstructed based on a revised supermatrix of morphological and molecular data [20]. We added CCNHM 1000, Olympicetus avitus [11] and Inermorostrum xenops [7] to this matrix, resulting in 114 taxa coded for 61 177 characters. A maximum parsimony phylogenetic analysis was performed in the application TNT [21], using default settings under a 'New Technology Search' except for setting the minimum length to be found 1000 times.…”

Section: Methodsmentioning

confidence: 99%

“…The specimen examined here, CCNHM 1000, is a small odontocete skull that lacks key synapomorphies of Xenorophidae [5], and otherwise closely resembles Olympicetus avitus [11] from the same locality. Phylogenetic analyses of Olympicetus avitus reconstruct it in a polytomy with Xenorophidae and the clade including Simocetus þ crown Odontoceti [11], or more closely related to crown Odontoceti (this study). The new material we describe here tests the hypothesis that echolocation involving ultrasonic frequencies evolved early in Odontoceti.…”

Section: Introductionmentioning

confidence: 94%

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Evidence for convergent evolution of ultrasonic hearing in toothed whales (Cetacea: Odontoceti)

et al. 2019

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Toothed whales (Cetacea: Odontoceti) are the most diverse group of modern cetaceans, originating during the Eocene/Oligocene transition approximately 38 Ma. All extant odontocetes echolocate; a single origin for this behaviour is supported by a unique facial source for ultrasonic vocalizations and a cochlea adapted for hearing the corresponding echoes. The craniofacial and inner ear morphology of Oligocene odontocetes support a rapid (less than 5 Myr) early evolution of echolocation. Although some cranial features in the stem odontocetes Simocetus and Olympicetus suggest an ability to generate ultrasonic sound, until now, the bony labyrinths of taxa of this grade have not been investigated. Here, we use µCT to examine a petrosal of a taxon with clear similarities to Olympicetus avitus . Measurements of the bony labyrinth, when added to an extensive dataset of cetartiodactyls, resulted in this specimen sharing a morphospace with stem whales, suggesting a transitional inner ear. This discovery implies that either the lineage leading to this Olympicetus -like taxon lost the ability to hear ultrasonic sound, or adaptations for ultrasonic hearing evolved twice, once in xenorophids and again on the stem of the odontocete crown group. We favour the latter interpretation as it matches a well-documented convergence of craniofacial morphology between xenorophids and extant odontocetes.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Evidence for convergent evolution of ultrasonic hearing in toothed whales (Cetacea: Odontoceti)

et al. 2019

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“…Echolocating toothed whales (Cetacea, Odontoceti) experienced an initial significant radiation during the Oligocene, being well documented by a consistent and continuously improving fossil record [ 1 – 11 ]. This broad diversity and morphological disparity was deeply sifted by selection near the Oligocene–Miocene boundary, when most of the stem odontocetes disappeared.…”

Section: Introductionmentioning

confidence: 99%

A new large squalodelphinid (Cetacea, Odontoceti) from Peru sheds light on the Early Miocene platanistoid disparity and ecology

et al. 2018

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The South Asian river dolphin (Platanista gangetica) is the only extant survivor of the large clade Platanistoidea, having a well-diversified fossil record from the Late Oligocene to the Middle Miocene. Based on a partial skeleton collected from the Chilcatay Formation (Chilcatay Fm; southern coast of Peru), we report here a new squalodelphinid genus and species, Macrosqualodelphis ukupachai. A volcanic ash layer, sampled near the fossil, yielded the 40Ar/39Ar age of 18.78 ± 0.08 Ma (Burdigalian, Early Miocene). The phylogenetic analysis places Macrosqualodelphis as the earliest branching squalodelphinid. Combined with several cranial and dental features, the large body size (estimated body length of 3.5 m) of this odontocete suggests that it consumed larger prey than the other members of its family. Together with Huaridelphis raimondii and Notocetus vanbenedeni, both also found in the Chilcatay Fm, this new squalodelphinid further demonstrates the peculiar local diversity of the family along the southeastern Pacific coast, possibly related to their partition into different dietary niches. At a wider geographical scale, the morphological and ecological diversity of squalodelphinids confirms the major role played by platanistoids during the Early Miocene radiation of crown odontocetes.

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“…However, Kiel et al [12] reported that LACM locality 5412 is ‘…on the beach terrace east of Murdock Creek…’. LACM locality 5412 is the type locality for the stem odontocete Olympicetus avitus [13]. However, field notes by one of the collectors (James L. Goedert) suggest that the holotype specimen of B. osedax is more accurately provenanced from LACM locality 5123, which is the type locality for the desmostylian Behemotops proteus [14].…”

Section: Methodsmentioning

confidence: 99%

“…This locality is the equivalent of LACM locality 5123 and is the type locality of Behemotops proteus [14]. Precise coordinates are 48°09'24.0″ N, 123°52'11.3″ W. Approximately 0.8 m east from the LACM locality 5412, which is the type locality of Olympicetus avitus [13]. LACM locality 5123 is Paleobiology Database locality number 58964.…”

Section: Systematic Palaeontologymentioning

confidence: 99%

Borealodon osedax, a new stem mysticete (Mammalia, Cetacea) from the Oligocene of Washington State and its implications for fossil whale-fall communities

2019

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Baleen whales (mysticetes) lack teeth as adults and instead filter feed using keratinous baleen plates. They do not echolocate with ultrasonic frequencies like toothed whales but are instead known for infrasonic acoustics. Both baleen and infrasonic hearing are separately considered key innovations linked to their gigantism, evolutionary success and ecological diversity. The earliest mysticetes had teeth, and the phylogenetic position of many so-called toothed mysticetes remains debated, including those belonging to the nominal taxonomic groups Llanocetidae, Mammalodontidae and Aetiocetidae. Here, we report a new stem mysticete, Borealodon osedax gen. et sp. nov., from the Oligocene of Washington State, USA. Borealodon preserves multi-cusped teeth with apical wear; microCT scans of the inner ear indicate that the minimum frequency hearing limit of Borealodon was similar to mammalodontids. Borealodon is not recovered within a monophyletic Mammalodontidae nor a monophyletic Aetiocetidae; instead, it represents an unnamed lineage of stem Mysticeti, adding to the diversity of stem mysticetes, especially across the Rupelian–Chattian boundary. Furthermore, the presence of a putative chemosynthetic bivalve along with Osedax , a bone-boring annelid, found in association with the type specimen of Borealodon , offer more insights into the evolution of deep-sea whale-fall communities.

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A new stem odontocete from the late Oligocene Pysht Formation in Washington State, U.S.A.

Cited by 14 publications

References 35 publications

Evidence for convergent evolution of ultrasonic hearing in toothed whales (Cetacea: Odontoceti)

Evidence for convergent evolution of ultrasonic hearing in toothed whales (Cetacea: Odontoceti)

A new large squalodelphinid (Cetacea, Odontoceti) from Peru sheds light on the Early Miocene platanistoid disparity and ecology

Borealodon osedax, a new stem mysticete (Mammalia, Cetacea) from the Oligocene of Washington State and its implications for fossil whale-fall communities

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