A new clade of putative plankton-feeding sharks from the Upper Cretaceous of Russia and the United States

Shimada, Kenshu; Popov, Evgeny; Siversson, Mikael; Welton, Bruce J.; Long, Douglas J.

doi:10.1080/02724634.2015.981335

Cited by 25 publications

(17 citation statements)

References 30 publications

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“…This timing, compatible with the late Cretaceous occurrence of † Pseudomegachasma (Shimada et al. ), a putative filter feeder not included in our analyses given uncertainties related to its phylogenetic position and trait attributes, suggest the possibility of elasmobranch filter feeding appearing much earlier than the Paleogene (Fig. D), during a period also known for elevated primary productivity (Price ; Puceat et al.…”

Section: Discussionsupporting

confidence: 74%

“…It is worth noting that a putative filter‐feeding lamniform, Pseudomegachasma , is known from the earliest late Cretaceous (Shimada et al. ). However, given that its exact phylogenetic position (placement in paraphyletic ‘Odontaspididae’) and body size are uncertain, we did not include it in our analyses.…”

Section: Resultsmentioning

confidence: 99%

“…]), and putative filter feeders (e.g., † Pseudomegachasma [Shimada et al. ]) or mesotherms (e.g., ctenacanthiforms [Maisey et al. ]) could not be included in our analyses.…”

Section: Discussionmentioning

confidence: 99%

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Evolutionary pathways toward gigantism in sharks and rays

et al. 2019

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Through elasmobranch (sharks and rays) evolutionary history, gigantism evolved multiple times in phylogenetically distant species, some of which are now extinct. Interestingly, the world's largest elasmobranchs display two specializations found never to overlap: filter feeding and mesothermy. The contrasting lifestyles of elasmobranch giants provide an ideal case study to elucidate the evolutionary pathways leading to gigantism in the oceans. Here, we applied a phylogenetic approach to a global dataset of 459 taxa to study the evolution of elasmobranch gigantism. We found that filter feeders and mesotherms deviate from general relationships between trophic level and body size, and exhibit significantly larger sizes than ectothermic‐macropredators. We confirm that filter feeding arose multiple times during the Paleogene, and suggest the possibility of a single origin of mesothermy in the Cretaceous. Together, our results elucidate two main evolutionary pathways that enable gigantism: mesothermic and filter feeding. These pathways were followed by ancestrally large clades and facilitated extreme sizes through specializations for enhancing prey intake. Although a negligible percentage of ectothermic‐macropredators reach gigantic sizes, these species lack such specializations and are correspondingly constrained to the lower limits of gigantism. Importantly, the very adaptive strategies that enabled the evolution of the largest sharks can also confer high extinction susceptibility.

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Section: Discussionsupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

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Evolutionary pathways toward gigantism in sharks and rays

et al. 2019

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“…Assignment to the Cetorhinidae may need revision (Cappetta et al, 2012, p. 330), and the conclusion that Pseudocetorhinus pickfordi is the earliest known filter-feeding shark (Duffin, 1999, p. 204) has recently been challenged (Shimada et al, 2015) since its teeth have a wider base, mesiodistally, than those of demonstrably planktivorous species from Upper Cretaceous and younger deposits of Russia and the USA. (Duffin, 1982a) Teeth of Synechodus rhaeticus are wide and multicuspid, each crown featuring a central cusp and at least one pair of lateral cusplets on either side (Fig.…”

Section: Pseudocetorhinus Pickfordi Duffin 1998amentioning

confidence: 99%

Microvertebrates from the classic Rhaetian bone beds of Manor Farm Quarry, near Aust (Bristol, UK)

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et al. 2015

Proceedings of the Geologists' Association

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Pseudocetorhinus pickfordi, absent in the basal bone bed, are relatively abundant in the four overlying bone-bearing units. These differences in faunal lists and in relative proportions probably do not reflect sampling, but some major differences in ecology and evolution.

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“…This species was erected for four isolated teeth obtained from a mid-Cretaceous (Cenomanian) deposit in Colorado, USA (Shimada, 2007). Later, Shimada et al (2014a) suggested that this species may not belong to the family Megachasmidae but to the family 'Odontaspidae', so its taxonomic position is still unsettled. This species is distinguishable from NMNS-PV 22659 in having a well developed nutrient groove and wide and flattened basal attachment surfaces of the tooth root (Shimada, 2007).…”

Section: Discussionmentioning

confidence: 99%