New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution

Boessenecker, Robert W.

doi:10.31233/osf.io/msdg2

Cited by 7 publications

(10 citation statements)

References 11 publications

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“…The difference in robustness of the mandible has been used qualitatively as a characteristic that sets apart male and female morphs of some Pliocene otariids (e.g., Callorhinus gilmorei ; Berta & Deméré, 1986 ; Boessenecker, 2011 ). Here, this character was explored quantitatively by comparing the ratio between width and height of the horizontal ramus at p4 ( Table S1 ).…”

Section: Discussionmentioning

confidence: 99%

Eotaria citrica, sp. nov., a new stem otariid from the “Topanga” formation of Southern California

Vélez‐Juarbe

2017

PeerJ

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A new taxon of stem otariid, Eotaria citrica sp. nov., is described from the upper Burdigalian to lower Langhian “Topanga” formation of Orange County, California. The new species is described from mandibular and dental remains that show a unique combination of plesiomorphic and derived characters. Specifically, it is characterized by having trenchant and prominent paraconid cusps in p3–m1, lingual cingula of p2–4 with faint crenulations, premolars and molars with vestigial metaconid, bilobed root of m2 and a genial tuberosity located under p3. Furthermore, additional material of the contemporaneous Eotaria crypta is described, providing new information on the morphology of this taxon. Both species of Eotaria represent the earliest stem otariids, reinforcing the hypothesis that the group originated in the north Eastern Pacific Region. At present, the “Topanga” Fm. pinniped fauna includes Eotaria citrica, Eotaria crypta, the desmatophocid Allodesmus sp., the odobenids Neotherium sp., Pelagiarctos sp. and includes the oldest records of crown pinnipeds in California. Overall this pinniped fauna is similar to the nearly contemporaneous Sharktooth Hill bonebed. However, unambiguous records of Eotaria are still missing from Sharktooth Hill. This absence may be due to taphonomic or paleoenvironmental factors. The new “Topanga” record presented here was integrated into an overview of the late Oligocene through early Pleistocene pinniped faunas of Southern California. The results show an overall increase in body size over time until the Pleistocene. Furthermore, desmatophocids were the largest pinnipeds during the middle Miocene, but were extinct by the beginning of the late Miocene. Odobenids diversified and became the dominant pinnipeds in late Miocene through Pleistocene assemblages, usually approaching or exceeding 3 m in body length, while otariids remained as the smallest taxa. This pattern contrasts with modern assemblages, in which the phocid Mirounga angustirostris is the largest pinniped taxon in the region, odobenids are extinct and medium and small size ranges are occupied by otariids or other phocids.

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Section: Discussionmentioning

confidence: 99%

Eotaria citrica, sp. nov., a new stem otariid from the “Topanga” formation of Southern California

Vélez‐Juarbe

2017

PeerJ

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“…, Uhen , Marshall and Goldbogen ). This is partly because of their simplified postcanine cheek teeth (molars and premolars), which are relatively ineffective tools for cutting prey compared to those of terrestrial Carnivora (Boessenecker ; Churchill and Clementz , ). In contrast, many terrestrial carnivorans ( e.g ., ursids and mustelids) secure large food items using their forelimbs while using their dentition to pierce, cut, and crush food, easily breaking it down into pieces small enough to swallow (Hiiemae and Crompton , ; Van Valkenburgh , ; Atkins ; Ungar ).…”

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confidence: 99%

Chew, shake, and tear: Prey processing in Australian sea lions (Neophoca cinerea)

Hocking

Ladds

Slip

et al. 2016

Marine Mammal Science

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Pinnipeds generally target relatively small prey that can be swallowed whole, yet often include larger prey in their diet. To eat large prey, they must first process it into pieces small enough to swallow. In this study we explored the range of prey‐processing behaviors used by Australian sea lions (Neophoca cinerea) when presented with large prey during captive feeding trials. The most common methods were chewing using the teeth, shaking prey at the surface, and tearing prey held between the teeth and forelimbs. Although pinnipeds do not masticate their food, we found that sea lions used chewing to create weak points in large prey to aid further processing and to prepare secured pieces of prey for swallowing. Shake feeding matches the processing behaviors observed in fur seals, but use of forelimbs for “hold and tear” feeding has not been previously reported for other otariids. When performing this processing method, prey was torn by being stretched between the teeth and forelimbs, where it was secured by being squeezed between the palms of their flippers. These results show that Australian sea lions use a broad repertoire of behaviors for prey processing, which matches the wide range of prey species in their diet.

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“…It is noteworthy that, considering our whole-genome phylogenies and last studies, Callorhinus diverged ca. 4 million years before the diversification of the rest of the family (Yonezawa et al 2009;Boessenecker 2011;Nyakatura and Bininda-Emonds 2012;Berta et al 2018).…”

Section: Otariidae Phylogenomicsmentioning

confidence: 99%

Phylogenomic Discordance in the Eared Seals is best explained by Incomplete Lineage Sorting following Explosive Radiation in the Southern Hemisphere

Lopes

Oliveira

Kessler

et al. 2020

Preprint

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The phylogeny and systematics of fur seals and sea lions (Otariidae) have long been studied with diverse data types, including an increasing amount of molecular data. However, only a few phylogenetic relationships have reached acceptance pointing at strong gene-tree species tree discordance. Divergence times in the group also vary largely between studies. These uncertainties impeded the understanding of the biogeographical history of the group, such as when and how trans-equatorial dispersal and subsequent speciation events occurred. Here we used high-coverage whole genome-wide sequencing for 14 of the 15 species of Otariidae to elucidate the phylogeny of the family and its bearing on the taxonomy and biogeographical history. Despite extreme topological discordance among gene trees, we found a fully supported species tree that agrees with the few well-accepted relationships and establishes monophyly of the genus Arctocephalus. Our data support a relatively recent trans-hemispheric dispersal at the base of a southern clade, which rapidly diversified into six major lineages between 3 to 2.5 Mya. Otaria diverged first, followed by Phocarctos and then four major lineages within Arctocephalus. However, we found Zalophus to be non-monophyletic, with California (Z. californianus) and Steller sea lions (Eumetopias jubatus) grouping closer than the Galapagos sea lion (Z. wollebaeki) with evidence for introgression between the two genera. Overall, the high degree of genealogical discordance was best explained by incomplete lineage sorting resulting from quasi-simultaneous speciation within the southern clade with introgresssion playing a subordinate role in explaining the incongruence among and within prior phylogenetic studies of the family.

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New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution

Cited by 7 publications

References 11 publications

Eotaria citrica, sp. nov., a new stem otariid from the “Topanga” formation of Southern California

Eotaria citrica, sp. nov., a new stem otariid from the “Topanga” formation of Southern California

Chew, shake, and tear: Prey processing in Australian sea lions (Neophoca cinerea)

Phylogenomic Discordance in the Eared Seals is best explained by Incomplete Lineage Sorting following Explosive Radiation in the Southern Hemisphere

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