Distribution and Diversity of Cretaceous Chelonioids

Hirayama, Ren

doi:10.1016/b978-012155210-7/50013-2

Cited by 67 publications

(112 citation statements)

References 5 publications

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“…coahuilaensis, late Campanian) appears after the extinction of protostegids, which had previously diversified in the Early Cretaceous ( Fig. 3; early Campanian; Hirayama, 1997). The timing of this origin, as well as the rapid diversification of pan-chelonioids in the Late Cretaceous in general, may correspond to the opening of ecological opportunities previously held by protostegids.…”

Section: Naromentioning

confidence: 99%

New sea turtle from the Miocene of Peru and the iterative evolution of feeding ecomorphologies since the Cretaceous

2010

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ABSTRACT-The seven species of extant sea turtles show a diversity of diets and feeding specializations. Some of these species represent distinctive ecomorphs that can be recognized by osteological characters and therefore can be identified in fossil taxa. Specifically, modifications to the feeding apparatus for shearing or crushing (durophagy) are easily recognizable in the cranium and jaw. New sea turtle fossils from the Miocene of Peru, described as a new genus and species (Pacifichelys urbinai n. gen. and n. sp.), correspond to the durophagous ecomorph. This new taxon is closely related to a recently described sea turtle from the middle Miocene of California, USA (Pacifichelys hutchisoni n. comb.), providing additional information on the osteological characters of this lineage. A phylogenetic analysis of Pacifichelys and other pan-chelonioid sea turtle lineages shows that at least seven lineages independently evolved feeding specialized for shearing or crushing. The iterative evolution of these morphologies is plausibly linked to ecological factors such as the development of seagrass communities and the opening of niches through extinction that occurred from the Cretaceous to the Miocene.

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Section: Naromentioning

confidence: 99%

New sea turtle from the Miocene of Peru and the iterative evolution of feeding ecomorphologies since the Cretaceous

2010

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“…While this phylogeny is similar to other previous studies (Hirayama 1998;Lehman & Tomlinson 2004), it is more pectinate. Toxochelys and Ctenochelys are no longer allied with derived Cheloniidae (sensu Hirayama 1994Hirayama , 1997Hirayama , 1998Joyce et al 2004;Lehman & Tomlinson 2004), but rather are reinterpreted as stem sea turtles outside crown Chelonioidea (an arrangement proposed elsewhere on braincase traits; see Gaffney and Meylan 1988;Hooks 1998). This hypothesis is further supported here by limb and girdle morphology, with Toxochelys and Ctenochelys retaining primitive postcranial features lost in crown chelonioids (figure 2): ischium with a well developed lateral process 64 , humerus with a capitellum that is upturned and shouldered 68 , first and second digits incorporated into paddle 78 , and femur with distinct trochanters 79 .…”

Section: Evolutionary Implicationsmentioning

confidence: 99%

“…However, their early evolutionary history remains largely unknown, as recent phylogenies do not recognize any definitive stem-group taxa. At present, all fossil sea turtles are assigned to one of two extant lineages within crown chelonioids (Hirayama 1994(Hirayama , 1997(Hirayama , 1998Joyce et al 2004;Lehman & Tomlinson 2004): one leads to living cheloniids (Pancheloniidae: Joyce et al 2004), and the other to living Dermochelys (Pandermochelys: Joyce et al 2004). The latter group includes the extinct Protostegidae, a diverse Cretaceous clade containing some spectacular Late Cretaceous giants (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…However, here we report on several exceptionally well preserved skulls belonging to one of the stratigraphically oldest and most primitive protostegids yet found. A reevaluation of sea turtle phylogeny incorporating these new fossils (re)establishes the primitive, shallow-water Toxochelys and Ctenochelys (Gaffney & Meylan 1988) as stem chelonioids; these taxa are currently placed within crown-chelonioids, along the lineage leading to living cheloniids (see Hirayama 1994Hirayama , 1997Hirayama , 1998.…”

Section: Introductionmentioning

confidence: 99%

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A primitive protostegid from Australia and early sea turtle evolution

Kear

Lee

2005

Biol. Lett.

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Sea turtles (Chelonioidea) are a prominent group of modern marine reptiles whose early history is poorly understood. Analysis of exceptionally well preserved fossils of Bouliachelys suteri gen. et sp. nov., a large-bodied basal protostegid (primitive chelonioid) from the Early Cretaceous (Albian) of Australia, indicates that early sea turtles were both larger and more diverse than previously thought. The analysis implies at least five distinct sea turtle lineages existed around 100 million years ago. Currently, the postcranially primitive Ctenochelys and Toxochelys are interpreted as crown-group sea turtles closely related to living cheloniids (e.g. Chelonia ); in contrast, the new phylogeny suggests that they are transitional (intermediate stem-taxa) between continental testudines and derived, pelagic chelonioids.

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“…However, due to the comparative rarity of vertebrate remains in any particular microfossil or invertebrate biozone, and the potential for non-recovery of an index taxon due to various geographical, ecological, or human factors, individual biozones are ineffective sampling windows. As a result, most analyses of marine vertebrate diversity consist either of local/regional studies with high temporal resolution (e.g., Sheldon, 1996;Mulder et al, 1998) or studies on far broader scales with concomitantly lower temporal resolution (e.g., Russell, 1993;Hirayama, 1997;Kriwet and Benton, 2004).…”

Section: Biostratigraphic Frameworkmentioning

confidence: 99%

Charting the Late Cretaceous seas: mosasaur richness and morphological diversification

Ross

2009

Journal of Vertebrate Paleontology

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ABSTRACT-Abundant, readily identifiable, and biostratigraphically resolved specimens make mosasaurs ideal candidates to test fluxes in generic richness and morphological trends among marine vertebrates during the late Cretaceous. More than 1800 globally distributed mosasaur specimens are allocated to fifteen substage-level stratigraphically correlated assemblages. These data are quantitatively analyzed to illuminate trends within the group. Following their first appearance in the Cenomanian, mosasaurs experienced a significant radiation in the Coniacian and Santonian. Richness levels continued increasing into the Maastrichtian while mosasaurs incrementally exploited new predatory niches recognized via accumulation of novel dental morphologies. Their extinction at the end of the Cretaceous occurred at the zenith of mosasaur morphological and ecological diversity.

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Distribution and Diversity of Cretaceous Chelonioids

Cited by 67 publications

References 5 publications

New sea turtle from the Miocene of Peru and the iterative evolution of feeding ecomorphologies since the Cretaceous

New sea turtle from the Miocene of Peru and the iterative evolution of feeding ecomorphologies since the Cretaceous

A primitive protostegid from Australia and early sea turtle evolution

Charting the Late Cretaceous seas: mosasaur richness and morphological diversification

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