Phylogenetic systematics of chelonioid sea turtles

Hirayama, Ren

doi:10.1111/j.1440-1738.1994.tb00116.x

Cited by 88 publications

(154 citation statements)

References 6 publications

(6 reference statements)

Supporting

Mentioning

145

Contrasting

Unclassified

Order By: Relevance

“…nov. (figure 1a-g and electronic supplementary material) was added to the most comprehensive published phylogenetic data set of sea turtles (Hirayama 1998), which was revised as follows. The chimera taxon Osteopygis was separated into two taxa (the cranial Euclastes and postcranial Osteopygis; Parham 2005), and additional postcranial characters for Euclastes scored from E. (Erquelinnesia) gosseleti (Lynch & Parham 2003;Hirayama 1994). Modifications were also made to the codings and/or character state definitions of 12 characters.…”

Section: Methodsmentioning

confidence: 99%

“…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%

See 3 more Smart Citations

A primitive protostegid from Australia and early sea turtle evolution

Kear

Lee

2005

Biol. Lett.

View full text Add to dashboard Cite

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.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Evolutionary Implicationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A primitive protostegid from Australia and early sea turtle evolution

Kear

Lee

2005

Biol. Lett.

View full text Add to dashboard Cite

show abstract

“…Diets of extinct Cretaceous protostegids remain speculative. Hirayama (1994) suggested that they might have been molluscivores, adapted to feeding on hard-shelled planktonic prey such as ammonites. This was based on their robust cranial morphology (e.g.…”

Section: Introductionmentioning

confidence: 99%

First gut contents in a Cretaceous sea turtle

Kear

2005

Biol. Lett.

View full text Add to dashboard Cite

Modern sea turtles utilize a variety of feeding strategies ranging from herbivory to omnivory. In contrast, the diets of fossil sea turtles are poorly known. This study reports the first direct evidence: inoceramid bivalve shell pieces (encased in phosphatic material) preserved within the body cavities of several small protostegid turtles (cf. Notochelone ) from the Lower Cretaceous of Australia. The shell fragments are densely packed and approximately 5–20 mm across. Identical shell accumulations have been found within coprolite masses from the same deposits; these are of a correct size to have originated from Notochelone , and indicate that benthic molluscs were regular food items. The thin, flexible inoceramid shells (composed of organic material integrated into a prismatic calcite framework) appear to have been bitten into segments and ingested, presumably in conjunction with visceral/mantle tissues and encrusting organisms. Although protostegids have been elsewhere interpreted as potential molluscivores, their primitive limb morphology is thought to have limited them to surface feeding. However, the evidence here that at least some forms were able to utilize benthic invertebrate prey indicates that, like modern sea turtles, protostegids probably exhibited a much broader range of feeding habits.

show abstract

Humerus osteology, myology, and finite element structure analysis of Cheloniidae

Krahl

Lipphaus

Sander

et al. 2019

The Anatomical Record

View full text Add to dashboard Cite

Adaptation of osteology and myology lead to the formation of hydrofoil foreflippers in Cheloniidae (all recent sea turtles except Dermochelys coriacea) which are used mainly for underwater flight. Recent research shows the biomechanical advantages of a complex system of agonistic and antagonistic tension chords that reduce bending stress in bones. Finite element structure analysis (FESA) of a cheloniid humerus is used to provide a better understanding of morphology and microanatomy and to link these with the main flipper function, underwater flight. Dissection of a Caretta caretta gave insights into lines of action, that is, the course that a muscle takes between its origin and insertion, of foreflipper musculature. Lines of action were determined by spanning physical threads on a skeleton of Chelonia mydas. The right humerus of this skeleton was micro-CT scanned. Based on the scans, a finite element (FE) model was built and muscle force vectors were entered. Muscle forces were iteratively approximated until a uniform compressive stress distribution was attained. Two load cases, downstroke and upstroke, were computed. We found that muscle wrappings (m. coracobrachialis magnus and brevis, several extensors, humeral head of m. triceps) are crucial in addition to axial loading to obtain homogenous compressive loading in all bone cross-sections. Detailed knowledge on muscle disposition leads to compressive stress distribution in the FE model which corresponds with the bone microstructure. The FE analysis of the cheloniid humerus shows that bone may be loaded mainly by compression if the bending moments are minimized.

show abstract

Phylogenetic systematics of chelonioid sea turtles

Cited by 88 publications

References 6 publications

A primitive protostegid from Australia and early sea turtle evolution

A primitive protostegid from Australia and early sea turtle evolution

First gut contents in a Cretaceous sea turtle

Humerus osteology, myology, and finite element structure analysis of Cheloniidae

Contact Info

Product

Resources

About