''Allopleuron'' is a genus of extinct

sea turtle Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, ...

, which measured long in life. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''Allopleuron hofmanni''. It is a basal member of the clade

Pancheloniidae Pancheloniidae is a clade of sea turtles It is defined as all turtles more closely related to cheloniid sea turtles than to dermochelyid ("leatherback") sea turtles.Joyce W.G, Parham J.F, Gauthier J.A. Developing a protocol for the conversion o ...

, closely related to ''

Protosphargis ''Protosphargis'' is an extinct genus of sea turtle from the Upper Cretaceous of Italy. It was first named by Capellini in 1884. Sources ''Protosphargis''at the Paleobiology Database The Paleobiology Database is an online resource for infor ...

''. Similar to ''Protosphargis'', it was characterized by shell reduction.

Fossil history

''Allopleuron'' lived from the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

(

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

age, 94.3 Ma) to the

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

(

Rupelian The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chattian ...

age, 28.4 Ma), therefore surviving the Cretaceous-Paleogene extinction event. Fossils have been found from Germany, the Netherlands, Kazakhstan and the United States.

Life history

''Allopleuron'' was believed to have used the

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pan ...

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical region ...

southern continental shelf as a breeding area. The modern day location of the breeding ground is along the coast of Asia. ''Allopleuron'' is believed to have eaten jellyfish, seaweed, or carcasses. It is believed that adult male ''Allopleuron'' lived off the coast of southeast Netherlands, and northeast Belgium due to the large amount of fossils in these areas. The area is believed to have been a sea grass meadow that was able to sustain the large population. The lack of remains from juvenile ''Allopleuron'' indicate that the young of the species lived elsewhere.

Phylogeny

Evers et al. (2019):

References

{{Cheloniidae Prehistoric turtles of Asia Late Cretaceous turtles Prehistoric turtles of Europe Prehistoric turtle genera Fossil taxa described in 1831 Taxa named by John Edward Gray Cheloniidae Extinct turtles Turtle genera