A new dolphin from the early Miocene of Patagonia (Argentina): insights into the evolution of Platanistoidea in the Southern Hemisphere

Viglino, Mariana; Buono, Mónica Romina; Cozzuol, Mário Alberto; Cuitiño, José Ignacio

doi:10.4202/app.00441.2017

Cited by 21 publications

(21 citation statements)

References 43 publications

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“…For the purposes of this study, we have defined the clade Platanistoidea as including the genera Waipatia , Otekaikea , Awamokoa , Zarhachis , Notocetus , Aondelphis , and Platanista (Viglino et al 2018a,b). These genera represent families that are usually recovered within this clade: Waipatiidae, Squalodelphinidae, and Platanistidae (for details on specimens used, see Table 1) (but note that some authors recovered waipatiids as stem Odontoceti; e.g., Lambert et al 2018; Bianucci et al 2020).…”

Section: Methodsmentioning

confidence: 99%

“…The tighter coiling is also a feature shared with the New Zealand taxa Awamokoa and Waipatia, both of which are very close to A. talen in the morphospace. Morphologically, the periotics of all three genera share some characteristics; for example: a vestigial dorsal crest (plesiomorphic characteristic), an elongated anterior bullar facet and a larger and squared posterior bullar facet, and an anterointernal sulcus on the dorsal surface of the anterior process (Fordyce 1994;Tanaka and Fordyce 2017;Viglino et al 2018b). Curiously, the inferred low-frequency limit is similar to that of stem mysticetes, Eschrichtius robustus, and balaenopterids (Ketten 1997;Ekdale and Racicot 2015;Park et al 2017a); significantly lower than the frequency range for extant odontocetes, except ziphiids (e.g., Ketten and Wartzok 1990;Ketten 1997Ketten , 2000Park et al 2016); and even lower than in P. gangetica (Kelkar et al 2018).…”

Section: Cochlear Evolution In Platanistoideamentioning

confidence: 99%

“…One living riverine species, P. gangetica , warrants special attention. This species is the sole extant representative of an otherwise diverse fossil group, the Platanistoidea (sensu de Muizon 1987), whose contents and phylogenetic relationships are still debated (e.g., Fordyce and de Muizon 2001; Boersma et al 2017; Tanaka and Fordyce 2017 and references therein; Viglino et al 2018a,b, 2020; Gaetán et al 2019; Bianucci et al 2020). The earliest fossil record of this group comes from the late Oligocene, reaching a peak in diversity by the early Miocene and a marked decrease by the middle–late Miocene (e.g., de Muizon 1987; Fordyce and de Muizon 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Allodelphinids are recorded in lower Miocene outcrops of the eastern and western margins of the North Pacific (Boersma and Pyenson 2016; Kimura and Barnes 2016). In Patagonia, lower Miocene outcrops (Cuitiño et al 2019) have produced two platanistoid species, the squalodelphinid Notocetus vanbenedeni and the platanistoid Aondelphis talen (Moreno 1892; Viglino et al 2018b; Viglino 2019); and two putative members of this group, Phoberodon arctirostris and Prosqualodon australis (Viglino et al 2018a; Gaetán et al 2019). Lower Miocene outcrops in Italy, France, Peru, and the United States hold other squalodelphinid taxa; and Miocene outcrops of mainly Europe and the United States record other extinct Platanistidae species (Paleobiology Database 2020; e.g., Barnes et al 2010; Lambert et al 2014; Godfrey et al 2017).…”

Section: Introductionmentioning

confidence: 99%

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Hearing from the ocean and into the river: the evolution of the inner ear of Platanistoidea (Cetacea: Odontoceti)

Viglino¹,

Gaetán²,

Buono³

et al. 2021

Paleobiology

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The inner ear of the two higher clades of modern cetaceans (Neoceti) is highly adapted for hearing infrasonic (mysticetes) or ultrasonic (odontocetes) frequencies. Within odontocetes, Platanistoidea comprises a single extant riverine representative, Platanista gangetica, and a diversity of mainly extinct marine species from the late Oligocene onward. Recent studies drawing on features including the disparate tympanoperiotic have not yet provided a consensus phylogenetic hypothesis for platanistoids. Further, cochlear morphology and evolutionary patterns have never been reported. Here, we describe for the first time the inner ear morphology of late Oligocene–early Miocene extinct marine platanistoids and their evolutionary patterns. We initially hypothesized that extinct marine platanistoids lacked a specialized inner ear like P. gangetica and thus, their morphology and inferred hearing abilities were more similar to those of pelagic odontocetes. Our results reveal there is no “typical” platanistoid cochlear type, as the group displays a disparate range of cochlear anatomies, but all are consistent with high-frequency hearing. Stem odontocete Prosqualodon australis and platanistoid Otekaikea huata present a tympanal recess in their cochlea, of yet uncertain function in the hearing mechanism in cetaceans. The more basal morphology of Aondelphis talen indicates it had lower high-frequency hearing than other platanistoids. Finally, Platanista has the most derived cochlear morphology, adding to evidence that it is an outlier within the group and consistent with a >9-Myr-long separation from its sister genus Zarhachis. The evolution of a singular sound production morphology within Platanistidae may have facilitated the survival of Platanista to the present day.

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Section: Methodsmentioning

confidence: 99%

Section: Cochlear Evolution In Platanistoideamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hearing from the ocean and into the river: the evolution of the inner ear of Platanistoidea (Cetacea: Odontoceti)

Viglino¹,

Gaetán²,

Buono³

et al. 2021

Paleobiology

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“…As mentioned above, the foramen singulare in mammals lies ventral to the transverse crest in the fundus of the internal acoustic meatus. The position of the foramen singulare relative to the transverse crest in cetaceans, however, has been variably interpreted among species: in some, it is considered as being dorsal to the transverse crest, and in others, being ventral to the crest (e.g., Aguirre‐Fernández & Fordyce, 2014; Boessenecker & Fordyce, 2015, 2017; Ichishima, Furusawa, Tachibana, & Kimura, 2019; Ichishima & Kimura, 2005; Kasuya, 1973; Kellogg, 1936; Kimura & Hasegawa, 2019; Lambert, Bianucci, & de Muizon, 2017; Lambert, Bianucci, & Urbina, 2014; Lambert, Godfrey, & Fitzgerald, 2019; Montañez‐Rivera & Hampe, 2020; O'Leary, 2010; Tanaka, Abella, Aguirre‐Fernández, Gregori, & Fordyce, 2017; Tanaka & Fordyce, 2014, 2015; Viglino, Buono, Gustein, Cozzuol, & Cuitiño, 2018).…”

Section: Introductionmentioning

confidence: 99%

The so‐called foramen singulare in cetacean periotics is actually the superior vestibular area

Ichishima

Kawabe

Sawamura

2021

The Anatomical Record

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It is nearly 100 years ago that the “foramen singulare” was first identified in cetacean periotics. Since then, the “foramen singulare” has been recognized in periotics of many cetacean species, extant or extinct. Surprisingly, however, it has never been confirmed if the foramen singulare in cetacean periotics is really homologous to that in other mammals. It is known that in mammals including humans the posterior ampullary nerve, which innervates the posterior semicircular duct, passes through the foramen singulare. We use an X‐ray micro‐CT scan to examine endocasts of the bony labyrinth of the inner ear of cetacean periotics, showing that the osseous canal extending from the so‐called foramen singulare goes toward the anterior bony ampulla, meaning that the alleged foramen singulare in cetacean periotics is really the superior vestibular area, through which the utriculoampullary nerve enters. The transverse crest is quite significant to identify each quadrant of the fundus of the internal acoustic meatus, but in many cetacean species the transverse crest is poorly developed, almost imperceptible in some species, and this could have brought confusion into the interpretation over the superior vestibular area and the foramen singulare. The bony septum separating the cerebral aperture of the facial canal from the foramen singulare is not the transverse crest, but the perpendicular crest. The foramen singulare is not a distinct foramen separated from the inferior vestibular area. Instead, the true foramen singulare opens near the inferior vestibular area in the internal acoustic meatus in cetacean periotics.

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First Toothless Platanistoid from the Early Miocene of Patagonia: the Golden Age of Diversification of the Odontoceti

et al. 2020

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A new dolphin from the early Miocene of Patagonia (Argentina): insights into the evolution of Platanistoidea in the Southern Hemisphere

Cited by 21 publications

References 43 publications

Hearing from the ocean and into the river: the evolution of the inner ear of Platanistoidea (Cetacea: Odontoceti)

Hearing from the ocean and into the river: the evolution of the inner ear of Platanistoidea (Cetacea: Odontoceti)

The so‐called foramen singulare in cetacean periotics is actually the superior vestibular area

First Toothless Platanistoid from the Early Miocene of Patagonia: the Golden Age of Diversification of the Odontoceti

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