The giant, spike-toothed salmon, &lt;em&gt;Oncorhynchus rastrosus&lt;/em&gt; and the “Proto-Tuolumne River” (early Pliocene) of Central California

Sankey, Julia; Biewer, Jacob; Basuga, Janus; Palácios, Francisco; Wagner, H.C.; Garber, Dennis

doi:10.5070/p9331033123

Cited by 3 publications

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“…In contrast, the premaxilla of † Oncorhynchus rastrosus does not demonstrate sexual dimorphism, though it does undergo ontogenetic morphological change in breeding males and females to an equal extent. In all specimens excavated from upstream, freshwater localities for this study and previously published studies, the premaxillae are bulbous with prominent, slightly worn dentition [ 6 , 8 , 9 ] (Cavender & Miller, 1972; Sankey, et al, 2016; Stearley & Smith, Salmonid Fishes From Mio-Pliocene Lake Sediments in The Western Snake River Plain and The Great Basin. Fishes of the Mio-Pliocene Western Snake River Plain and Vicinity: Museum of Zoology, University of Michigan, 2016).…”

Section: Discussionmentioning

confidence: 99%

“…Fishes of the Mio-Pliocene Western Snake River Plain and Vicinity: Museum of Zoology, University of Michigan, 2016). The premaxilla of specimens recovered from coastal marine environments is much less bulbous, close in size to the tooth it bears [ 8 ] (Sankey, et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

“…[ 47 ] (Grubb & d’Huart, 2010). A key feature on the premaxillae that allows us to orient isolated premaxilla is the wing-like thin, bony-plate on the posterodorsal aspect, which was worn down, overlooked, or misinterpreted in isolated, previously described specimens [ 6 , 8 , 9 ] (Cavender & Miller, 1972; Sankey, et al, 2016; Stearley & Smith, Salmonid Fishes From Mio-Pliocene Lake Sediments in The Western Snake River Plain and The Great Basin. Fishes of the Mio-Pliocene Western Snake River Plain and Vicinity: Museum of Zoology, University of Michigan, 2016).…”

Section: Discussionmentioning

confidence: 99%

“…While overall size of the premaxilla and spike increased when migrating and maturing [ 8 ] (Sankey, et al, 2016), the relative position of the premaxilla during the oceanic phase remains uncertain. It is possible that there was some rotation from a more “traditional” position in marine spike-tooth salmon prior to moving instream.…”

Section: Discussionmentioning

confidence: 99%

“…It should be noted that the accessory teeth are significantly proportionally smaller than the premaxillary teeth of marine † O . rastrosus described by Sankey et al [ 8 ] (Sankey, et al, 2016) and appear to differ in tooth structure.…”

Section: Systematic Paleontologymentioning

confidence: 99%

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From sabers to spikes: A newfangled reconstruction of the ancient, giant, sexually dimorphic Pacific salmon, †Oncorhynchus rastrosus (SALMONINAE: SALMONINI)

Claeson,

Sidlauskas,

Troll

et al. 2024

PLoS ONE

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The impressive †Oncorhynchus rastrosus of the Pacific Northwest’s Miocene and Pliocene eras was the largest salmonid ever to live. It sported a hypertrophied premaxilla with a pair of enlarged teeth which the original describers reconstructed as projecting ventrally into the mouth, leading them to assign the species to “Smilodonichthys,” a genus now in synonymy. Through CT reconstruction of the holotype and newly collected specimens, we demonstrate that the famed teeth projected laterally like tusks, not ventrally like sabers or fangs. We also expand the original description to characterize sexual dimorphism in mature, breeding individuals. Male and female †Oncorhynchus rastrosus differ in the form of the vomer, rostro-dermethmoid-supraethmoid, and dentary, much as do other extant species of Oncorhynchus. Male specimens possess a more elongate vomer than do females, and female vomers have concave ventral surfaces and prominent median dorsal keels. The dentary of females has no evidence of a kype, though some specimens of †O. rastrosus have a non-uniform density mesial to the tooth bed, which we interpret as a male kype. Unlike extant Oncorhynchus, male and female †O. rastrosus do not differ in premaxilla shape. Because male and females possess hypertrophied premaxillae and lateral premaxillary spikes, the former common name “Sabertoothed Salmon” no longer reflects our understanding of the species’ morphology. Accordingly, we redub †O. rastrosus the Spike-Toothed Salmon and postulate that its spikes were multifunctional, serving as defense against predators, in agonism against conspecifics, and as a practical aid to nest construction.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Systematic Paleontologymentioning

confidence: 99%

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From sabers to spikes: A newfangled reconstruction of the ancient, giant, sexually dimorphic Pacific salmon, †Oncorhynchus rastrosus (SALMONINAE: SALMONINI)

Claeson,

Sidlauskas,

Troll

et al. 2024

PLoS ONE

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Reconstructing the mass and thermal ecology of North American Pleistocene tortoises

Esker¹,

Forman²,

Butler³

2019

Paleobiology

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Researchers often interpret the presence of tortoises in Pleistocene assemblages as evidence of an interglacial age, based on an assumption that these fossils indicate thermic climates, as modern giant tortoises require. Since the Paleocene, tortoises have been common components of terrestrial fossil assemblages and have repeatedly evolved species of giant size. Whereas extant giant tortoises are found only on islands off the coasts of South America and Africa, at least two species persisted in North America until the terminal Pleistocene. These tortoises, Hesperotestudo crassiscutata and Gopherus “hexagonatus,” both of which reached carapace lengths of >1 m, were distributed across the southern United States. This study provides new metrics to derive quantitative weight estimates from measurements of the tortoise shell. The linear measurements of 69 anatomical features of the shells of 108 live tortoises indicate that the regression between straight carapace length and weight is most significant, with a maximum r2 > 0.99. This regression is useful for tortoises that weigh between 1.8 and 339 kg. This mass estimate, coupled with a heat dissipation rate derived from thermoregulation modeling, provides estimates of how long tortoises can maintain a viable body temperature at low ambient temperatures. Depending on size, a tortoise can survive a maximum of 2.3 to 33 hours of freezing temperatures, which corresponds to a mean annual temperature ≥22°C and a mean winter low temperature ≥7.5°C. This analysis infers warmer temperatures at Pleistocene sites with fossil tortoise occurrences than previous qualitative estimates.

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First bone-cracking dog coprolites provide new insight into bone consumption in Borophagus and their unique ecological niche

Wang

White

Balisi

et al. 2018

eLife

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Borophagine canids have long been hypothesized to be North American ecological ‘avatars’ of living hyenas in Africa and Asia, but direct fossil evidence of hyena-like bone consumption is hitherto unknown. We report rare coprolites (fossilized feces) of Borophagus parvus from the late Miocene of California and, for the first time, describe unambiguous evidence that these predatory canids ingested large amounts of bone. Surface morphology, micro-CT analyses, and contextual information reveal (1) droppings in concentrations signifying scent-marking behavior, similar to latrines used by living social carnivorans; (2) routine consumption of skeletons; (3) undissolved bones inside coprolites indicating gastrointestinal similarity to modern striped and brown hyenas; (4) B. parvus body weight of ~24 kg, reaching sizes of obligatory large-prey hunters; and (5) prey size ranging ~35–100 kg. This combination of traits suggests that bone-crushing Borophagus potentially hunted in collaborative social groups and occupied a niche no longer present in North American ecosystems.

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The giant, spike-toothed salmon, <em>Oncorhynchus rastrosus</em> and the “Proto-Tuolumne River” (early Pliocene) of Central California

Cited by 3 publications

References 0 publications

From sabers to spikes: A newfangled reconstruction of the ancient, giant, sexually dimorphic Pacific salmon, †Oncorhynchus rastrosus (SALMONINAE: SALMONINI)

From sabers to spikes: A newfangled reconstruction of the ancient, giant, sexually dimorphic Pacific salmon, †Oncorhynchus rastrosus (SALMONINAE: SALMONINI)

Reconstructing the mass and thermal ecology of North American Pleistocene tortoises

First bone-cracking dog coprolites provide new insight into bone consumption in Borophagus and their unique ecological niche

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