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... characters 3, 8e9; differs from "T." dissolutus and "Aspideretes" maortuensis by character 3, 6 and 9; differs from "T." shiluutulensis by characters 4, 6, 8e9 and differs from Aspideretoides riabinini by characters 3e5 and 9. See Table 2 for further differences between "Trionyx" jixiensis and other Cretaceous trionychids. Measurements: see Table 1. ...
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A series of small-sized fossil turtles were collected from Beckles' Pit, Durlston Bay, Dorset, United Kingdom in 1856 from a sediment package referable to the Early Cretaceous (Berriasian) Purbeck Group. The two primary accounts that previously documented these turtles concluded that they represent the juveniles of the coeval early pleurosternid Pl...
The Prionochelys nauta from the Cretaceous has great importance to geological history and the fossil record. This species originated in the coastal seas of the Gulf Coast according to the findings of fragmented bones. This species contains a synapmorphy that distinguished them, which was the serrated edges along the middle of their shell. The disco...
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... Softshell turtles (Pan-Trionychidae) are an unusual clade of reptiles easily recognized in the fossil record by their reduced carapace that lacks pygals and peripherals, the lack of scutes, a reduced plastron, and a distinctive shell surface texture that allows even shell fragments to be diagnosed to the group (Hutchison et al., 1986;Meylan, 1987;Scheyer et al., 2007;Vitek & Joyce, 2015;Georgalis & Joyce, 2017). The clade has a rich and relatively continuous record in North America since the Santonian (Adrian et al., 2019;Brinkman, 2003;Edgar et al., 2022;Vitek & Joyce, 2015), but apparently originated in Asia during the Early Cretaceous (Georgalis, 2021;Georgalis & Joyce, 2017;Li et al., 2015). The clade has a geographically widespread fossil record with specimens reported from Asia, Europe, and Africa, and to a lesser degree from Australia and South America (Georgalis, 2021;Georgalis & Joyce, 2017;Li et al., 2015;Vitek & Joyce, 2015). ...
... The clade has a rich and relatively continuous record in North America since the Santonian (Adrian et al., 2019;Brinkman, 2003;Edgar et al., 2022;Vitek & Joyce, 2015), but apparently originated in Asia during the Early Cretaceous (Georgalis, 2021;Georgalis & Joyce, 2017;Li et al., 2015). The clade has a geographically widespread fossil record with specimens reported from Asia, Europe, and Africa, and to a lesser degree from Australia and South America (Georgalis, 2021;Georgalis & Joyce, 2017;Li et al., 2015;Vitek & Joyce, 2015). ...
Hutchemys rememdium is a poorly understood softshell turtle (Trionychidae) from the mid Paleocene of the Williston Basin of North America previously known only from postcranial remains. A particularly rich collection of previously undescribed material from the Tiffanian 4 North American Land Mammal Age (NALMA) of North Dakota is here pre-sented consisting of numerous shells that document new variation, some non-shell postcrania, and cranial remains,which are described based on 3D models extracted from micro-CT data. Although the observed shell variation weakens previously noted differences with the younger species Hutchemys arctochelys from the Clarkforkian NALMA, the two taxa are still recognized as distinct. Parsimony and Bayesian phylogenetic analyses reaffirm the previously challenged placement of Hutchemys rememdium within the clade Plastomenidae, mostly based on novel observations of cranial characters made possible by the new material and the micro-CT data. The new topology supports the notion that the well-ossified plastron of plastomenids originated twice in parallel near the Cretaceous/Paleogene boundary, once in the Hutchemys lineage and once in the Gilmoremys/Plastomenus lineage. Hutchemys rememdium is notable for being the only documented species of trionychid in the mid Paleocene of the Williston Basin. The presence of multiple individuals in a carbonaceous claystone indicates this taxon lived in swamps and lakes and its expanded triturating surface suggests it had a durophagous diet.
... Shao et al., , 2018Li et al., 2019). However, these fossil turtles have been less commonly collected outside the typical western Liaoning area of the Jehol Biota (e.g., Ma, 1986;Li et al., 2015;Li and Tong, 2017;Wu et al., 2018). Recently, as the first record of the Mesozoic turtles from Jilin Province, the sinemydid Ordosemys has been reported from the Early Cretaceous Hengtongshan Formation of Xingling Town, Meihekou City (Wu et al., 2018). ...
Recently, a vertebrate assemblage of the Jehol Biota has been reported from the Early Cretaceous Hengtongshan Formation of Xingling Town, Meihekou City, Jilin Province, China. It is dominated by the fishes Lycoptera and Sinamia and the sinemydid turtle Ordosemys. Here, we describe the turtle specimens and referral to Ordosemys liaoxiensis, otherwise known from the older Yixian Formation of the Jehol Biota. It is characterized by a subcircular shell, wide vertebral scales, well-developed plastral fenestrae, and a major contribution from the xiphiplastra to enclose the hypo-xiphiplastral fenestra. As the first Mesozoic turtle of Jilin Province, this record represents the first tetrapod to indicate the presence of the Jehol Biota in the region. Given the geographic and temporal distance from the Yixian Formation, future collections from the Hengtongshan Formation have good potential for evaluating spatiotemporal patterns of the Jehol Biota.
... Aspideretoides foveatus (Leidy 29 ) was rescored based on more complete material. The topology of the molecular backbone constraint used in previous morphological analyses is relatively poorly resolved 20,21,25 . We here employ a composite tree of more recent and better supported phylogenies [30][31][32] . ...
... All fossil ingroup taxa were designated as floaters. Instead of a hypothetical outgroup used in previous studies 2,20,21,25 we added Adocus lineolatus Cope 33 and Carettochelys insculpta Ramsay 34 to the matrix to avoid assuming the ancestral condition a priori. ...
Pan-trionychids or softshell turtles are a highly specialized and widespread extant group of aquatic taxa with an evolutionary history that goes back to the Early Cretaceous. The earliest pan-trionychids had already fully developed the “classic” softshell turtle morphology and it has been impossible to resolve whether they are stem members of the family or are within the crown. This has hindered our understanding of the evolution of the two basic body plans of crown-trionychids. Thus it remains unclear whether the more heavily ossified shell of the cyclanorbines or the highly reduced trionychine morphotype is the ancestral condition for softshell turtles. A new pan-trionychid from the Early Cretaceous of Zhejiang, China, Perochelys hengshanensis sp. nov., allows a revision of softshell-turtle phylogeny. Equal character weighting resulted in a topology that is fundamentally inconsistent with molecular divergence date estimates of deeply nested extant species. In contrast, implied weighting retrieved Lower Cretaceous Perochelys spp. and Petrochelys kyrgyzensis as stem trionychids, which is fully consistent with their basal stratigraphic occurrence and an Aptian-Santonian molecular age estimate for crown-trionychids. These results indicate that the primitive morphology for soft-shell turtles is a poorly ossified shell like that of crown-trionychines and that shell re-ossification in cyclanorbines (including re-acquisition of peripheral elements) is secondary.
... Despite the geological age of the locality, it is difficult to determine whether this species is a stem or a crown trionychid because of the high levels of homoplasy among trionychids (Li et al., 2015a). 'Trionyx' jixiensis from the Chengzihe Formation (Aptian-Albian) of northeastern China also possessed a carapace similar to that of crown trionychids (Li et al., 2015b). 'Trionyx' kyrgyzensis from the lower-middle Albian of the Kylodzhun locality, Kyrgyzstan (Nessov, 1995), is the oldest known trionychid outside East Asia. ...
... The FPDM specimens constitute one of the oldest records of Trionychidae during the Barremian-Aptian interval. In addition to this and Kappachelys from the Hauterivian-Aptian of Japan (Hirayama et al., 2012), possible stem trionychids have been reported from China (Li et al., 2015a(Li et al., , 2015b; however, no trionychids are yet known from other regions prior to the Albian (Fig. 7). This is not direct evidence of an eastern Asian origin of Trionychidae because the fossil record of non-marine turtles from the Hauterivian-Barremian is generally quite incomplete; however, an Asian origin is supported by the lack of trionychids in Lower Cretaceous non-marine turtle fossil localities outside Central and East Asia. ...
Herein we report morphologically and histologically diagnostic trionychid specimens from the Barremian–Aptian (129.4–113.0 Ma) of Japan. One specimen (FPDM-V9487) is an associated skeleton that consists of a scapula, a humerus, an ischium, and hypoplastra. The limb and girdle bones are similar in morphology to those of modern trionychids. The hypoplastron also resembles that of modern trionychids; however, it is distinctive in that it completely lacks callosities. The other three new specimens are fragmentary costals that show a reduction in the shell bones and an absence of scute sulci. Two of the newly reported costals and FPDM-V0127 were examined histologically. Bone fiber bundles organized in a plywood-like structure, which is unique to trionychids, were identified. Fossil occurrence data indicate that morphologically and histologically typical trionychids already inhabited the coastal region of Asia (e.g., western Japan) as early as the Aptian. In contrast, the Hauterivian–Aptian stem trionychid Kappachelys okurai from Japan does not show a plywood-like shell microstructure, suggesting that K. okurai could be the earliest-branching taxon of known stem trionychids or a carettochelyid. Our paleobiogeographic compilation suggests that the spread of wetlands in the Northern Hemisphere and the high global temperature during the middle Cretaceous (Aptian–Turonian, 125.0–89.8 Ma) might have contributed to the dispersal of trionychids from Asia, allowing for the establishment of this modern freshwater reptilian fauna.
Citation for this article: Nakajima, Y., I. G. Danilov, R. Hirayama, T. Sonoda, and T. M. Scheyer. 2017. Morphological and histological evidence for the oldest known softshell turtles from Japan. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1278606.
... A potentially older specimen from the Barremian-Aptian of Japan with an extremely reduced shell lacking epidermal callosities on the hypoplastra further supports this hypothesis (Nakajima et al. in press). In future analyses, it may be worth using no outgroup and running an unrooted analysis (Li et al. 2015b;Joyce et al. 2016). ...
Although fossils of Trionychidae are found as far back as the Early Cretaceous, their evolutionary history, including the origin of the crown clade, is poorly understood. Here, we use a microCT scan of the skull of ‘Trionyx’ kyrgyzensis from the late Early Cretaceous (Albian) of Kyrgyzstan as the basis for a thorough redescription of the cranial morphology of this species. New information includes the pattern of cranial circulation, which is comparable to all extant trionychids. A unique combination of cranial and postcranial characters of ‘Trionyx’ kyrgyzensis allows us to establish for it a new genus Petrochelys gen. nov. The data regarding Petrochelys kyrgyzensis are incorporated into a phylogenetic analysis. When Petrochelys kyrgyzensis is analysed without including additional, extinct taxa, it is placed in a highly derived position within the extant Nilssonia. However, the addition of five Cretaceous–Palaeogene taxa breaks up hypothesized long branches and results in more basal positions for Petrochelys kyrgyzensis within recovered trees. All results support the hypothesis that Petrochelys kyrgyzensis is a crown trionychid and a member of Trionychinae. Our findings highlight the importance of including multiple extinct taxa in phylogenetic analyses prior to using any of those taxa as calibration points in divergence dating estimates.
http://zoobank.org/urn:lsid:zoobank.org:pub:592B98BF-87DF-48A8-8AA2-543AAD21FC95
The taxonomy of the soft-shell turtle Rafetus bohemicus (Liebus, 1930), family Triony-chidae, subfamily Trionychinae, is revised based on new and previously mentioned material (including the type material) from the Early Miocene (Burdigalian, MN 3) sites of the Most Basin, Czechia. Given that the diagnosis was so far based only on plastral elements, here we focused on the cranial material and combined our study with previously published data on postcranial elements. 3D models of the skulls derived from CT scans allow us to provide the first complete skull description of R. bohemicus, including several new cranial diagnostic characters of the species. Our results not only enable the distinction of the trionychid genera Trionyx and Rafetus, both recorded from Central Europe during the Early Miocene, but further allow us to provide an emended diagnosis for R. bohemicus. We confirm the conclusions of a previous study according to which Trionyx pontanus, T. preschenensis, T. aspidiformis, and T. elongatus are nomina dubia. R. bohemicus from Břešt'any (MN 3) represents the oldest record of this genus in Europe as well as the oldest occurrence of the genus.
... Extinct trionychids can be easily identified from shell fragments based on the unique sculpture of the shell elements and the plywood-like structure of the external cortex of the costals ). Pan-trionychids likely originated in Asia during the Early Cretaceous because they were widely distributed on that continent during that time (Li et al. 2015a(Li et al. , 2015b(Li et al. , 2017Brinkman et al. 2017;Vitek et al. 2018). ...
... Globally, the earliest pan-trionychid fossil material is found in the Lower Cretaceous (Aptian) of Asia, where Pan-Trionychidae likely originated (Hirayama et al. 2000(Hirayama et al. , 2013Joyce et al. 2013;Li et al. 2015aLi et al. , 2015b. Pan-Trionychidae dispersed to North America by the Cenomanian, as documented by a single neural from the Cedar Mountain Formation in Utah (Fiorillo 1999), and subsequently diversified in North America during the Late Cretaceous (Hirayama et al. 2000;Joyce et al. 2009). ...
The pre-Campanian trionychid fossil record in North America is composed of highly fragmentary specimens, which are often not identifiable beyond Pan-Trionychidae. Here, we describe a new species of plastomenid soft-shelled turtle based on a partial shell (ROM 56647) from the Santonian Milk River Formation of southern Alberta, estimated at approximately 84 Ma. This represents the oldest relatively complete shell of a trionychid from North America. Plastomenidae, a pan-trionychid clade known only from the fossil record, is classically characterized by the complete suturing of its posterior plastral bones along the midline, a crescent-shaped entoplastron, and enlarged costals VIII. ROM 56647 has a unique combination of plastomenid characters (i.e., mid-line contact of hypoplastra and xiphiplastra, anteroposteriorly long eighth costal) and apomorphies (an emarginate nuchal, enlarged tubercles on the carapace, a wide pygal notch with a straight anterior edge, and a fused hyo-hypoplastron) that allows us to identify it as a new taxon, Jimemys glaebosus gen. et sp. nov. Phylogenetic analysis places J. glaebosus within Plastomenidae as the sister taxon to a clade containing Plastomenus, Helopanoplia, and Hutchemys. This phylogenetic position implies that Aspideretoides foveatus Leidy, 1856, Atoposemys, and Gilmoremys, all of which are more basal within Plastomenidae, had ghost lineages extending at least to the Santonian. As the oldest pan-trionychid that is diagnostic to the species level in North America, J. glaebosus provides new insights into both the early evolution of trionychids in North America and the biodiversity of southern Alberta during a poorly sampled time in the Late Cretaceous of North America.
The Mesozoic turtle fossils from China provided
crucial information for understanding the origin and early
evolution of turtles (Li and Tong, 2015; Zhou and Rabi, 2015; Li
et al., 2018). From the Early Cretaceous non-marine deposits of
China, many well-preserved or little-damaged fossils of the
Sinemydidae and ‘soft-shelled’ turtles had been discovered and
described (Brinkman et al., 2013, 2017; Li et al., 2015; Shao et
al., 2018; Li et al., 2019). To date, up to eleven genera of the
Family Sinemydidae from Early Cretaceous strata of China have
been reported; they are listed as follows: (1) the Genus Sinemys
includes Sinemys lens (Wiman, 1930) from the Mengyin
Formation of Shandong, Sinemys gamera (Brinkman and Peng,
1993) and Sinemys brevispinus (Tong and Brinkman, 2013) both
from the Luohandong Formation of Inner Mongolia. (2)
Manchurochelys manchoukuoensis was originally discovered in
western Liaoning, Yixian Formation (Endo and Shikama, 1942).
(3) Xiaochelys ningchengensis from Yixian Formation in Inner
Mongolia is important for providing information indicating that
sinemydids mostly share symplesiomorphies with sea turtles is
an artefact (Zhou and Rabi, 2015). (4) More recently, a new
species, Jeholochelys lingyuanensis, has been erected with many
specimens found within the Jiufotang Formation in Lingyuan of
Liaoning (Shao et al., 2018). (5) The species Liaochelys
jianchangensis was from the Jiufotang Formation in western
Liaoning (Zhou, 2010a). (6) Kirgizemys kansuensis, from
Jiayuguan, Gansu Province, is the only known species of the
genus reported in China (Danilov et al., 2006). (7) Genus
Yumenemys, also excavated from Gansu, is represented by the
holotype of Yumenemys inflatus from the Early Cretaceous
(Bohlin, 1953). (8) Changmachelys bohlini, another species
found in Gansu Province, was excavated from the Xiagou
Formation (Brinkman et al., 2013). (9) Genus Dracochelys,
whose holotype Dracochelys bicuspis was from the Tugulu
Group of Xinjiang (Gaffney and Ye, 1992). (10) Genus Wuguia
includes two species, Wuguia hutubeiensis (Matzke et al., 2004)
and Wuguia efremovi (Danilov and Sukhanov, 2006), which
were both found in Xinjiang. (11) Genus Ordosemys has four
currently recognized species: Ordosemys leios from Inner
Mongolia, Luohandong Formation (Brinkman and Peng, 1993);
O. donghai from the Chengzihe Formation of Heilongjiang
Province (Brinkman et al., 2008); O. liaoxiensis discovered in
Beipiao, Liaoning Province, in the Yixian Formation (Tong et
al., 2004) and O. brinkmania from the Tugulu Group in Xinjiang
Province (Danilov and Parham, 2007). As most of those genera
have discovered recently, an updated phylogenetic analysis of
this clade is yet to be completed. Given the taxic and
morphological diversity of the taxa, their comparative
paleobiology and paleoecology could also be important research
objectives in the future. Trionychidae is a crown group of soft-
shell turtles, with the oldest known record from the Early
Cretaceous. A total of four species are known from the Early
Cretaceous of China. These include Sinamyda fuchienensis from
the Early Cretaceous Hekou Formation of Fujian, southern China
(Chkhikvadze, 2000); “Trionyx” jixiensis from Chengzihe
Formation of Helongjiang (Li et al., 2015); and Perochelys
lamadongensis from the Jiufotang Formation of Liaoning,
northeastern China (Li et al., 2015). The fourth taxon,
Perochelys hengshanensis has been described recently from
Hengshan Formation of Zhejiang Province, southeastern China
(Brinkman et al., 2017). The above listed turtles are all members
of the Jehol Biota sensu lato. The available evidence suggests
that they originated and diversified in a relatively short period of
time, during the transition from the Late Jurassic to early Early
Cretaceous, and some of them appear to be distributed widely;
the sinemydid turtles, are stem cryptodires, recorded in
Cretaceous to Paleocene deposits in Asia and North America.
The eleven genera listed above are distributed mainly in northern
China, including provinces like Liaoning, Heilongjiang,
Shandong, Inner Mongolia, Gansu, and Xinjiang. Although the
oldest member of this family, Hongkongochelys, occurs in the
Late Jurassic of Neijiang, Sichuan Province. The
Xinjiangchelyidae, a crown Cryptodire clade dominated a larger
area than Sinemydidae during the Middle-Late Jurassic, and
appears to have been replaced by the Sinemydidae in East Asia
during the Cretaceous, occurred in SE Asia, Central Asia, and
Western and Southern Europe. Therefore, detailed research on
patterns of diversity and biogeography of Late Mesozoic turtles
in Asia will provide a better understanding their evolutionary
history.
A new xinjiangchelyid turtle, Kalasinemys prasarttongosothi n. gen. n. sp., is described on the basis of skull and shell material from the Upper Jurassic Phu Kradung Formation at Phu Noi locality, Kalasin Province, in NE Thailand. This second xinjiangchelyid turtle from Phu Noi is distinct from Phunoichelys thirakhupti by the smooth shell surface, the presence of a cervical notch, and vertebral 1 narrower than nuchal. The skull presents an arterial system characteristic of the Xinjiangchelyidae (basal Eucryptodira), and its outline is similar to that of Annemys spp. known from the Middle–Late Jurassic of China and Mongolia, but distinct from the latter mainly by the wider triturating surface, smaller foramen palatinum posterius and the shape of the prefrontal and frontal, as well as that of the basisphenoid and basioccipital. Based on the turtle assemblages, the correlation with mainland Asia further supports a Late Jurassic age for the lower part of the Phu Kradung Formation where Phu Noi site is located stratigraphically. Our study provides new insight on the evolution of the basal eucryptodiran turtles in Asia.
Turtles of the clade Pan-Trionychidae have a rich fossil record in the Old World, ranging from the Early Cretaceous (Hauterivian) to the Holocene. The clade most probably originated in Asia during the Early Cretaceous but spread from there to the Americas and Europe by the Late Cretaceous, to India and Australia by the Eocene, and to Afro-Arabia by the Neogene. The presence of a single pan-cyclanorbine in the Late Cretaceous (Maastrichtian) of Asia provides a minimum estimate for the age of the trionychid crown. As preserved, diversity was relatively high in Asia during the Late Cretaceous, but the subsequent, strong decline is likely a preservational bias, as extant faunas are relatively rich, especially throughout Asia. The range of trionychids contracted southward in Europe over the course of the Neogene, and the group is now locally extirpated. The group is now similarly absent from Arabia and Australia. A taxonomic review of the 180 named
Old World taxa finds 42 nomina valida, 38 nomina invalida, 88 nomina dubia, 11 nomina nuda, and 1 nomen suppressum.
