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A new pleurodiran turtle is described here. It is identified as attributable to Bothremydidae. The new taxon comes from an upper Maastrichtian (Upper Cretaceous) outcrop located in Southwestern Niger (in the Indamane Mount area, belonging to the Abalak Department of the Tahoua Region). Abalakemys chapmanae gen. et sp. nov. is identified by an almost complete large shell of about 65 cm in length. The new bothremydid turtle is recognized as a member of Bothremydodda, showing several autapomorphies (an exclusive ornamental pattern on the plate's outer surface, covered by small depressions; small fourth pleural scutes, only anteromedially reaching the sixth pair of costal plates; and noticeably wedged posterior plastral lobe toward the posterior region), as well as a unique combination of characters for this clade. This turtle could belong to Nigeremydini, a poorly understood Maastrichtian to Paleocene lineage of Bothremydodda, which integrates large coastal taxa that inhabited the African Trans-Saharan seaway, and for which shell information is currently extremely limited. [ABSTRACT FROM AUTHOR]

Pleurodira represent one of the two clades that compose the crown Testudines, and their temporal range is Late Jurassic–present. However, knowledge about the neuroanatomy of extinct pleurodires is still very limited. In this context, scarce neuroanatomical information about the Cretaceous clade Euraxemydidae is currently available, limited to some characters of the Moroccan Cenomanian Dirqadim schaefferi. In the present work, we perform the detailed neuroanatomical study of its sister taxon, the Brazilian Albian Euraxemys essweini, based on the analysis of the skull of its holotype and only known individual of the species. The detailed virtual three-dimensional reconstruction of all its cranial bones is performed, also improving the information about its osseous anatomy. The different neuroanatomical cavities (i.e., cranial, nasal, and labyrinthic ones) and canals (i.e., nervous and circulatory ones) are compared with those identified thus far for other extinct and extant members of the Pleurodira in order to characterize the neuroanatomy of the extinct clade Euraxemydidae in detail. [ABSTRACT FROM AUTHOR]

We herein describe Paraharmotrema karinganiense n. gen., n. sp. Dutton & Bullard (Liolopidae Dollfus, 1934) from specimens infecting the intestine of the serrated hinged terrapin (Pelusios sinuatus), east African black mud turtle (Pelusios subniger) (both Nwanedzi River, Mozambique), and South African helmeted terrapin (Pelomedusa galeata) (North-western Zululand, KwaZulu-Natal Province, South Africa). The new genus can be easily differentiated from the other accepted liolopid genera (Liolope Cohn, 1902; Helicotrema Odhner, 1912; Harmotrema Nicoll, 1914; Dracovermis Brooks & Overstreet, 1978) by the combination of having a linguliform body approximately 6–9 × longer than wide, tegumental spines/scales, a minute ventral sucker located in the anterior 1/7−1/8 of the body, deeply lobed testes that are transverse and abut the caeca (spanning the intercaecal space), a uterus that is lateral to the anterior testis (not ventral to the anterior testis), a lobed ovary that is dextral and nearest the posterior testis, and a vitellarium that does not extend anteriad to the level of the ventral sucker and that does not fill the intercaecal space. Nucleotide sequences of large subunit ribosomal DNA (28S) and internal transcribed space region (ITS2) from all analyzed specimens of the new species were identical, respectively; the 28S sequences differed from that of Liolope copulans Cohn, 1902 and from that of Harmotrema laticaudae Yamaguti, 1933 by 103 (8%) and 105 (8%) nucleotides, respectively. The 28S phylogenetic analysis recovered the new genus sister to a clade comprising L. copulans and H. laticaudae. A key to liolopid genera is provided herein. The present study comprises the first nucleotide-based phylogenetic placement of Harmotrema and first record of a liolopid from South Africa or Mozambique. It is the first proposal of a new liolopid genus in 43 yrs, and it documents a second liolopid genus from P. subniger while tripling the number of liolopid turtle hosts reported from the continent of Africa.

A turtle carapace, identified as Algorachelus cf. peregrina (Pleurodira, Pelomedusoides, Bothremydidae), is reported here from the shallow marine deposits of the Boundary Marls Unit (Utrillas Group), in Estercuel (Teruel Province, northeastern Spain). These levels are identified as deposited during the Lower to Upper Cretaceous transition (late Albian to earliest Cenomanian). This is the oldest record of a bothremydid turtle in Laurasia, documenting that the first dispersal of pelomedusoid turtles from Gondwana to Laurasia occurred earlier than previously identified, most probably in the Early Cretaceous. Pleurodiran turtles always require warm climatic conditions and are mainly freshwater forms. This dispersal was favored by climate change (global warming) that began in the Albian, as well as by the habitat change of the Algorachelus lineage from freshwater to coastal marine environments. • The oldest bothremydid remain in Europe is presented here. • The shell was found in shallow marine deposits. • It evidences the oldest dispersal of a pelomedusoid turtle from Gondwana to Laurasia. • The Albian-early Cenomanian global warming favored the dispersal. • The adaptation of the lineage of Algorachelus to marine environments also favored it. [ABSTRACT FROM AUTHOR]

The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been reported from the Mata Amarilla Formation (Cenomanian), the Cerro Fortaleza Formation (Campanian–Maastrichtian), and the Chorrillo Formation (early Maastrichtian). In this contribution, we examined all the turtle remains recovered from six localities in the Mata Amarilla Formation, nearby Mata Amarilla farm (Santa Cruz Province, Argentina). These fossils are housed at the “Padre Molina” Museum in Río Gallegos, Santa Cruz. Most of the carapace and plastral remains are conferred to an indeterminate small species of cf. Prochelidella sp., while the remaining fragments are attributed to a mid-sized species of an indeterminate Chelidae. Prochelidella spp. is a group of turtles distributed in Chubut, Río Negro, Neuquén, and Mendoza provinces, ranging from the Aptian to the Maastrichtian, with two main gaps (late Albian and Coniacian–Santonian). The recognition of cf. Prochelidella sp. in the Austral-Magallanes Basin extends the geographic range of this group more than 500 km south to the previously known southernmost record of Prochelidella, Pr. argentinae, from the Golfo San Jorge Basin (Chubut, Argentina).

A new pleurodiran turtle is described here. It is identified as attributable to Bothremydidae. The new taxon comes from an upper Maastrichtian (Upper Cretaceous) outcrop located in Southwestern Niger (in the Indamane Mount area, belonging to the Abalak Department of the Tahoua Region). Abalakemys chapmanae gen. et sp. nov. is identified by an almost complete large shell of about 65 cm in length. The new bothremydid turtle is recognized as a member of Bothremydodda, showing several autapomorphies (an exclusive ornamental pattern on the plate’s outer surface, covered by small depressions; small fourth pleural scutes, only anteromedially reaching the sixth pair of costal plates; and noticeably wedged posterior plastral lobe toward the posterior region), as well as a unique combination of characters for this clade. This turtle could belong to Nigeremydini, a poorly understood Maastrichtian to Paleocene lineage of Bothremydodda, which integrates large coastal taxa that inhabited the African Trans-Saharan seaway, and for which shell information is currently extremely limited.

Pleurodira represent one of the two clades that compose the crown Testudines, and their temporal range is Late Jurassic–present. However, knowledge about the neuroanatomy of extinct pleurodires is still very limited. In this context, scarce neuroanatomical information about the Cretaceous clade Euraxemydidae is currently available, limited to some characters of the Moroccan Cenomanian Dirqadim schaefferi. In the present work, we perform the detailed neuroanatomical study of its sister taxon, the Brazilian Albian Euraxemys essweini, based on the analysis of the skull of its holotype and only known individual of the species. The detailed virtual three-dimensional reconstruction of all its cranial bones is performed, also improving the information about its osseous anatomy. The different neuroanatomical cavities (i.e., cranial, nasal, and labyrinthic ones) and canals (i.e., nervous and circulatory ones) are compared with those identified thus far for other extinct and extant members of the Pleurodira in order to characterize the neuroanatomy of the extinct clade Euraxemydidae in detail.

We herein describe Paraharmotrema karinganiense n. gen., n. sp. Dutton & Bullard (Liolopidae Dollfus, 1934) from specimens infecting the intestine of the serrated hinged terrapin (Pelusios sinuatus), east African black mud turtle (Pelusios subniger) (both Nwanedzi River, Mozambique), and South African helmeted terrapin (Pelomedusa galeata) (North-western Zululand, KwaZulu-Natal Province, South Africa). The new genus can be easily differentiated from the other accepted liolopid genera (Liolope Cohn, 1902; Helicotrema Odhner, 1912; Harmotrema Nicoll, 1914; Dracovermis Brooks & Overstreet, 1978) by the combination of having a linguliform body approximately 6–9 × longer than wide, tegumental spines/scales, a minute ventral sucker located in the anterior 1/7−1/8 of the body, deeply lobed testes that are transverse and abut the caeca (spanning the intercaecal space), a uterus that is lateral to the anterior testis (not ventral to the anterior testis), a lobed ovary that is dextral and nearest the posterior testis, and a vitellarium that does not extend anteriad to the level of the ventral sucker and that does not fill the intercaecal space. Nucleotide sequences of large subunit ribosomal DNA (28S) and internal transcribed space region (ITS2) from all analyzed specimens of the new species were identical, respectively; the 28S sequences differed from that of Liolope copulans Cohn, 1902 and from that of Harmotrema laticaudae Yamaguti, 1933 by 103 (8%) and 105 (8%) nucleotides, respectively. The 28S phylogenetic analysis recovered the new genus sister to a clade comprising L. copulans and H. laticaudae. A key to liolopid genera is provided herein. The present study comprises the first nucleotide-based phylogenetic placement of Harmotrema and first record of a liolopid from South Africa or Mozambique. It is the first proposal of a new liolopid genus in 43 yrs, and it documents a second liolopid genus from P. subniger while tripling the number of liolopid turtle hosts reported from the continent of Africa. [Display omitted] • Description of Paraharmotrema karinganiense n. gen., n. sp. Dutton & Bullard (Liolopidae Dollfus, 1934) from African turtles. • First nucleotide-based phylogenetic placement of Harmotrema and first record of a liolopid from South Africa or Mozambique. • Documents a second liolopid genus from P. subniger. • Triples the number of liolopid turtle hosts reported from the continent of Africa. • Comments on Brooks and Overstreet 1978. [ABSTRACT FROM AUTHOR]

Bothremydidae is the most abundant clade of turtles in the Campanian and Maastrichtian (Upper Cretaceous) fossil record of southwestern Europe. Several members of Foxemydina Gaffney, Tong & Meylan, 2006 are known in an area that includes Southern France and the North-Eastern half of Spain. The problematic 'Polysternon' atlanticum is the worst characterized, lacking a diagnosis that allows its specific validity to be confirmed, and whose generic attribution has been recognized as doubtful. Its presence was exclusively proposed in its type locality, the upper Campanian quarry of Laño, in Treviño County (Burgos Province, North of Spain). Despite the fact that knowledge about Bothremydidae has markedly increased after the description of 'Polysternon' atlanticum Lapparent de Broin & Murelaga, 1996, no new information about this species has been published since the 1990s. The analysis of abundant unpublished material of the bothremydid from Laño allows us to confirm the validity of this species. As a consequence of this study, it is not only identified in its type locality, but also in other Spanish regions and in the south of France. The diversity of Bothremydidae Baur, 1891 in the Upper Cretaceous of Europe is lower than previously considered. Thus, the species 'Iberoccitanemys convenarum' (Laurent, Tong & Claude, 2002), originally defined for the French record, and subsequently also identified in Spain, is identified here as a synonym of the species described in Laño. An emended diagnosis for the upper Campanian to upper Maastrichtian, Iberoccitanemys atlanticum (Lapparent de Broin & Murelaga, 1996) n. comb., is proposed. [ABSTRACT FROM AUTHOR]

Dortokidae is an endemic family of stem-pleurodiran turtles, known exclusively from the Cretaceous and early Paleogene of Europe. Here we describe a new dortokid taxon from the Upper Cretaceous (Maastrichtian) Sînpetru Formation of the southern Haţeg Basin, Romania. The type material of Dortoka vremiri sp. nov. comprises a well-preserved carapace and a nearly complete plastron as well as the in situ right scapula and right pubis. Phylogenetic analyses performed to assess the position and interrelationships of Dortoka vremiri sp. nov. within Dortokidae as well as within the wider Pleurodira recovered the new taxon firmly nested within Dortokidae, and together with other dortokids, placed along the stem lineage of pleurodires. Our analysis provides evidence for allopatric speciation in Dortoka through the presence of two distinct lineages – an eastern and a western European lineage, respectively. A similar east/west disjunct distribution pattern has also been established previously for several vertebrate groups such as other turtles, dinosaurs and mammals, probably resulting from isolation due to the particular palaeogeographical setting of the Late Cretaceous European Archipelago. The phylogeny demonstrates local survival of Dortoka across the K-Pg boundary as the sister-taxon of D. vremiri is D. botanica from the uppermost Paleocene deposits of Romania and points to geographical selectivity, as the western lineage of Dortoka went extinct before the Paleogene. Osteology and novel taphonomical data imply a semi-terrestrial lifestyle for Kallokibotion bajazidi, a turtle occurring in coeval faunas with the aquatic and smaller-sized D. vremiri and most likely going extinct at the K-Pg boundary. Altogether, this pattern is consistent with selective extinction of terrestrial taxa previously observed for other continental vertebrate assemblages across the end-Cretaceous mass extinction with only two other examples from turtles. [ABSTRACT FROM AUTHOR]

In this work we focus on the fossil record of turtles and tortoises from the Chubut Province, in Patagonia, Argentina. This record is the richest, most diverse, the longest and continuous in the country and one of the most important in the continent. In this work, we present and study new fossils from all known clades of turtles from the province, coming from targeted field campaigns, as well as from past investigations, placed in a comprehensive and detailed chronostratigraphic context. In Chubut, more than 241 occurrences of turtles from at least 223 collection points are known, spanning from the Toarcian (Jurassic) to the Tortonian (Miocene). we manage to fill some of the gaps in the fossil record, complete the anatomical knowledge of many taxa, explore new geographical areas, and present some important highlights. Among these, the record of the oldest pan-chelid turtles indicates the significant potential of the sedimentary deposits of Chubut. Furthermore, we discuss the changes in the diversity and faunal turnovers of the various turtle clades in this region during the last 180 Ma and across important events during the Cretaceous/Paleocene and Oligocene/Miocene boundaries.

The Maevarano Formation in northwestern Madagascar has yielded a series of exceptional fossils over the course of the last three decades that provide important insights into the evolution of insular ecosystems during the latest Cretaceous (Maastrichtian). We here describe a new genus and species of pelomedusoid turtle from this formation, Sahonachelys mailakavava, based on a nearly complete skeleton. A phylogenetic analysis suggests close affinities of Sahonachelys mailakavava with the coeval Madagascan Sokatra antitra. These two taxa are the only known representatives of the newly recognized clade Sahonachelyidae, which is sister to the speciose clade formed by Bothremydidae and Podocnemidoidae. A close relationship with coeval Indian turtles of the clade Kurmademydini is notably absent. A functional assessment suggests that Sahonachelys mailakavava was a specialized suction feeder that preyed upon small-bodied invertebrates and vertebrates. This is a unique feeding strategy among crown pelomedusoids that is convergent upon that documented in numerous other clades of turtles and that highlights the distinct evolutionary pathways taken by Madagascan vertebrates.

Four turtle taxa are previously documented from the Cenomanian Arlington Archosaur Site (AAS) of the Lewisville Formation (Woodbine Group) in Texas. Herein, we describe a new side-necked turtle (Pleurodira), Pleurochayah appalachius gen. et sp. nov., which is a basal member of the Bothremydidae. Pleurochayah appalachius gen. et sp. nov. shares synapomorphic characters with other bothremydids, including shared traits with Kurmademydini and Cearachelyini, but has a unique combination of skull and shell traits. The new taxon is significant because it is the oldest crown pleurodiran turtle from North America and Laurasia, predating bothremynines Algorachelus peregrinus and Paiutemys tibert from Europe and North America respectively. This discovery also documents the oldest evidence of dispersal of crown Pleurodira from Gondwana to Laurasia. Pleurochayah appalachius gen. et sp. nov. is compared to previously described fossil pleurodires, placed in a modified phylogenetic analysis of pelomedusoid turtles, and discussed in the context of pleurodiran distribution in the mid-Cretaceous. Its unique combination of characters demonstrates marine adaptation and dispersal capability among basal bothremydids. [ABSTRACT FROM AUTHOR]

Pleurodiran turtles are relatively abundant in the Eocene record of Europe, being mostly represented by Podocnemididae. Two genera have been identified. The most abundant and diverse is the well-known freshwater Neochelys. The other is Eocenochelus. The record of this poorly-known genus is very scarce. It is the only representative of the Upper Cretaceous to extant Erymnochelyini (i.e., a new tribe proposed here for the 'Erymnochelys group of turtles') interpreted as a littoral form, and the only one known outside Africa. The finding of the only complete shell of Eocenochelus hitherto identified is presented here. It comes from the Castejón de Sobrarbe-41 site, in the middle Eocene (Lutetian) of the Sobrarbe Formation of the Ainsa Basin (Huesca, Spain). The sedimentary environment of the site is compatible with its attribution to a littoral form. It is attributed to the type species of the genus, Eocenochelus eremberti, so far exclusively known by two partial shells from the middle Eocene of the Franco-Belgian Basin. Therefore, the paleobiogeographic distribution of this species is markedly increased, from the southern area of the North Sea to the Bay of Biscay. This finding provides new anatomical data on the species Eocenochelus eremberti and on its poorly known genus. [ABSTRACT FROM AUTHOR]

Six species of freshwater turtles dominate the Chaco-Pampa Plain in southern South America and their parasites have been relatively understudied, with most records concentrated in Brazil. Particularly in Argentina, there are only scattered records of parasites for most of the turtles that inhabit the region, leaving a large knowledge gap. The purpose of the present contribution is to increase the knowledge of the internal parasites of six species of freshwater turtles from Argentina, after 15 years of fieldwork, by providing new hosts and additional geographic records for many host-parasite relationships. Some molecular sequences of the studied parasites were provided as a tool for better species identification. We processed 433 stomach and fecal samples from live individuals and visceral and soft tissue samples from 54 dissected turtles collected from a wide range and different ecoregions. We found 6230 helminths belonging to 18 taxa (one cestode, 11 digeneans and six nematodes). Fourteen new parasite-host associations are reported here, and for the first time parasites are recorded for Phrynops williamsi. This work contributes significantly to the knowledge of the parasitofauna in freshwater turtles in Argentina, providing a detailed list of parasites present in each turtle species and reporting molecular characters for future studies.

In this paper, we describe pleurodire turtle material from the island of Sardinia, Italy, originating from two Eocene localities of the Cixerri Formation. The more complete among the two specimens bears strong resemblance with the continental Western European Eocenochelus eremberti and is tentatively referred to the same species, while the second, less complete specimen is only provisionally referred to the genus Eocenochelus. The new Sardinian turtles add to the so far scarcely documented fossil record of pleurodires in Italy, while it ranks as among the very few Paleogene vertebrates known from the island. The identification of the widespread Eocene Western European genus Eocenochelus in the fossil record of Sardinia supports recent palaeogeographic reconstructions of the island, according to which the Sardinia-Corsica Massif was located rather close to mainland Europe and was subjected to a significant, counterclockwise rotation during the Paleogene. [ABSTRACT FROM AUTHOR]

In this paper, we describe pleurodire turtle material from the island of Sardinia, Italy, originating from two Eocene localities of the Cixerri Formation. The more complete among the two specimens bears strong resemblance with the continental Western European Eocenochelus eremberti and is tentatively referred to the same species, while the second, less complete specimen is only provisionally referred to the genus Eocenochelus. The new Sardinian turtles add to the so far scarcely documented fossil record of pleurodires in Italy, while it ranks as among the very few Paleogene vertebrates known from the island. The identification of the widespread Eocene Western European genus Eocenochelus in the fossil record of Sardinia supports recent palaeogeographic reconstructions of the island, according to which the Sardinia-Corsica Massif was located rather close to mainland Europe and was subjected to a significant, counterclockwise rotation during the Paleogene.

Background Jainemys pisdurensis comb. nov. is an extinct pleurodiran turtle from the Late Cretaceous (Maastrichtian) of India, previously referred to Carteremys and Shweboemys. The holotype, an eroded skull, had been collected near the village of Pisdura, south of Nagpur, in Maharashtra State, while all referred shell material originates from coeval sediments exposed at the nearby village of Dongargaon. Initial estimates believed this turtle to either be an early representative of Podocnemididae or a basal representative of Pelomedusoides. Methods We here figure and describe all specimens that had previously been referred to Jainemys pisdurensis comb. nov. We furthermore re-evaluate the validity of this fossil turtle and explore its phylogenetic relationships within Pleurodira. Results The holotype of Jainemys pisdurensis comb. nov. displays a morphology that differs substantially from that originally reported. Most notably, the palatines only have a minor contribution to the broad triturating surfaces but have a broad midline contact with each other, the pterygoids only have a midline contact of intermediate length and do not contact the opisthotics posteriorly, the basisphenoid is broad and short, and the opisthotics do not contribute to the flooring of the cavum acustico-jugulare. The referred shell material also displays a morphology different from that reported originally, in particular in that vertebral I does not contribute to the anterior margin of the carapace while the nuchal does. Phylogenetic analysis places the cranial material within the bothremydid clade Kurmademydini, while the shell material is placed in an unresolved polytomy at the base of this clade. Jainemys pisdurensis is confirmed to be a valid species of pleurodiran turtle, but the high diversity of coeval kurmademydines in India demands removal of the postcranial remains from this taxon. The realization that all valid species of Late Cretaceous (Maastrichtian) turtles from India form a clade supports the hypothesis that India was physically separated from the rest of Gondwana at this time.

Background: Jainemys pisdurensis comb. nov. is an extinct pleurodiran turtle from the Late Cretaceous (Maastrichtian) of India, previously referred to Carteremys and Shweboemys. The holotype, an eroded skull, had been collected near the village of Pisdura, south of Nagpur, in Maharashtra State, while all referred shell material originates from coeval sediments exposed at the nearby village of Dongargaon. Initial estimates believed this turtle to either be an early representative of Podocnemididae or a basal representative of Pelomedusoides. Methods: We here figure and describe all specimens that had previously been referred to Jainemys pisdurensis comb. nov. We furthermore re-evaluate the validity of this fossil turtle and explore its phylogenetic relationships within Pleurodira. Results: The holotype of Jainemys pisdurensis comb. nov. displays a morphology that differs substantially from that originally reported. Most notably, the palatines only have a minor contribution to the broad triturating surfaces but have a broad midline contact with each other, the pterygoids only have a midline contact of intermediate length and do not contact the opisthotics posteriorly, the basisphenoid is broad and short, and the opisthotics do not contribute to the flooring of the cavum acustico-jugulare. The referred shell material also displays a morphology different from that reported originally, in particular in that vertebral I does not contribute to the anterior margin of the carapace while the nuchal does. Phylogenetic analysis places the cranial material within the bothremydid clade Kurmademydini, while the shell material is placed in an unresolved polytomy at the base of this clade. Jainemys pisdurensis is confirmed to be a valid species of pleurodiran turtle, but the high diversity of coeval kurmademydines in India demands removal of the postcranial remains from this taxon. The realization that all valid species of Late Cretaceous (Maastrichtian) turtles from India form a clade supports the hypothesis that India was physically separated from the rest of Gondwana at this time. [ABSTRACT FROM AUTHOR]

Pleurodires are less diverse than cryptodires, together forming the two major lineages of crown turtles. Their fossil record, however, is rich. A particularly large number of fossil pleurodires, many belonging to the Podocnemidoidae, has been recovered from the Upper Cretaceous Bauru Group outcrops of south‐central Brazil. Herein we describe an additional pleurodire from this region, Amabilis uchoensis gen. et sp. nov., based on a partially preserved skull. A. uchoensis is recognized as belonging to the Podocnemidoidae by the small entrance to the antrum postoticum and completely developed cavum pterygoidei, being unique among other non‐podocnemidid podocnemidoids for its medially open fenestra postotica and absent basioccipital–opisthotic contact. Our cladistic analysis places A. uchoensis as a sister taxon to Hamadachelys + other podocnemidoids. We further explore the neuroanatomy of side‐necked turtles with the aid of micro‐computed tomography of specimens of the main pleurodiran lineages. Our data shed light on the different carotid circulation patterns in pleurodires, and we propose new phylogenetic characters to describe the neuroanatomical variation of the group. Optimization of these characters shows two independent acquisitions of a foramen for the palatal branch of the carotid in chelids and podocnemidoids, and a unique loss of the vidian nerve canal in chelids, in turtles in general. [ABSTRACT FROM AUTHOR]

The bothremydid pleurodiran turtle Taphrosphys congolensis is a member of Taphrosphyina from the Paleocene of the Cabinda Province (Congo Basin, Angola). Very few specimens corresponding to elements of its shell have been so far figured. Abundant unpublished remains are analyzed in this paper. As a consequence, several regions of the shell are figured and characterized here for the first time, and intraspecific variability is recognized for several characters. Previous authors proposed some putative differences between the shells of Taphrosphys congolensis and the North American Paleocene Taphrosphys sulcatus. The increase in the knowledge about the shell of this African form allows us to refute most of them, the shell of both forms being recognized as more similar than previously identified. Thus, the identification of the genus Taphrosphys as restricted to three forms (i.e. the skull taxon Taphrosphys ippolitoi, and the skull and shell forms T. congolensis and T. sulcatus) is supported, and the record unquestionably attributable to this genus is modified from the Upper Cretaceous–Eocene lapse of time to the Paleocene exclusively. [ABSTRACT FROM AUTHOR]

Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2–11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni.

Background Piramys auffenbergi was described as an emydine turtle based on a well-preserved skull retrieved from late Miocene deposits exposed on Piram Island, India. The description and figures provided in the original publication are vague and do not support assignment to Emydinae. This taxon has mostly been ignored by subsequent authors. Material and Methods We reexamine the holotype specimen, provide an extensive description and diagnosis for Piramys auffenbergi, and include this taxon in a global character-taxon matrix for Pleurodira. Results The presence of a processus trochlearis pterygoidei conclusively shows pleurodiran affinities for Piramys auffenbergi. Inclusion of this taxon in a phylogenetic analysis retrieves it within Stereogenyini closely related to the Asian taxa Shweboemys pilgrimi and Brontochelys gaffneyi. Discussion Our reexamination of the holotype of Piramys auffenbergi confidently rejects the original assessment of this taxon as an emydine testudinoid and conclusively shows affinities with the pleurodiran clade Stereogenyini instead. Even though most taxa from this lineage are thought to be coastal turtles, all Asian stereogenyines were collected from continental deposits, suggesting a more diverse paleoecology for the group.

Here, we define a research program using primordial skull characters for broad scale phylogenetic comparisons, particularly for amniotes. There are many chondrocranium descriptions in the literature, encompassing many clades of vertebrates. The definition of a comparable "tempus optimum" for fully formed chondrocrania, as developed herein, will enable discrete character definition in the sense of phylogenetic systematics. The "tempus optimum" is a time period in which the nose region shows full chondrification and the basicranium has not yet changed in its anatomy by ossification processes. For studies on heterochrony, changes in the developmental timing through evolution, the available data in the literature are insufficient. Anatomical standardizations, traceable methodological approaches and clear definitions of comparable developmental stages are needed. Moreover, for profound homology assertions of chondrocranial structures, ontogeny needs to be traced from early mesenchymal condensation, through several stages of cartilage development, up to postnatal stages, in which ossifications are already present. A holistic observation, including hard and soft tissue anatomy, is of paramount importance to generate hypotheses of homology with much explanatory power and to derive conclusions on functional morphology. For that, traditional histological methodology is needed. We exemplify the suggested approach in two case studies on the disputed laterosphenoid in turtles and crocodiles and on the homology of pila antotica in a pleurodire turtle, and, using here defined criteria, we formulate hypotheses on their homology. [ABSTRACT FROM AUTHOR]

The two extant clades of turtles, Pleurodira and Cryptodira, can be distinguished by the fact that the pelvic elements of pleurodire turtles are extensively sutured to both the carapace and plastron whereas the pelvic elements of cryptodire turtles are not. Pleurodire shells are also generally flatter than those of cryptodires. These distinctive features could potentially contribute to differences in the strength of the shell in these two clades, but quantitative assessments are lacking. We asked the following questions: How do the sutured pelvic elements of Pelomedusa subrufa (Pleurodira) affect the strength of the turtle's shell? Does the height of the turtle shell affect shell strength? Are there differences in the strength of the shells of pleurodires and cryptodires living in the same geographic regions? We developed finite element models of pleurodire and cryptodire shells and used them to assess the effects of various morphologies and loading regimes on shell stress. The pleurodire model without pelvic elements had higher maximum and average stresses for all load cases, and thus lower strength, than the model with pelvic elements, showing that sutured pelvic elements increase the strength of the shell. Increases in shell height increased shell strength. No differences in strength were found between pleurodire and cryptodire species living in the same geographic regions, indicating that the two clades might be evolving in response to the same selective pressures or requirements, but doing so in different ways. Overall, pleurodires and cryptodires are both able to increase the strength of their shells, but the morphological characteristics that they use to do so differ between the clades. [ABSTRACT FROM AUTHOR]

The poorly known pleurodiran turtle 'Stereogenys' libyca (Podocnemididae, Erymnochelyinae) is studied in this paper. It was defined in lower Oligocene levels of the Fayum Depression (Egypt), its presence in the upper Eocene levels of the same area being confirmed here. Its holotype corresponds to an almost complete and well preserved shell, that was until recently considered to be lost. No photograph of material attributable to this species had hitherto been published. Thus, the current knowledge about it was exclusively based on the limited information published more than a century ago. The recently rediscovered holotype, and also more than fifteen additional historical but unpublished specimens recognized here as attributable to this species, are studied in this paper. This species is attributed to a new genus, Andrewsemys, and the new combination Andrewsemys libyca is proposed. http://www.zoobank.org/urn:lsid:zoobank.org:pub:6D87831A-4510-4A3E-A624-C40FD644F448 [ABSTRACT FROM AUTHOR]

Abstract Araripemydidae is a clade of freshwater pleurodiran turtles originally described in South America, where it is represented by the Brasilian Aptian–Albian Araripemys barretoi. Two potential members of this lineage were defined in an Aptian level of Africa, in Gadoufaoua (Niger): Taquetochelys decorata , described from several isolated plates, and Lagaremys tenerensis , known from an almost complete skeleton. The review of the Araripemydidae record, and the analysis of the intraspecific variability present in that and in other clades of Pleurodira, allow me to refute their attribution to two different forms. ' L. tenerensis ' is here recognized as a junior synonym of T. decorata. Therefore, the priority of T. decorata is demonstrated, as well as its attribution to Araripemydidae. The almost complete skeletal anatomy of the two currently recognized members of this Aptian–Albian clade (i.e. the African T. decorata and the South American A. barretoi) is well known, which is uncommon for the Cretaceous pleurodiran turtles. [ABSTRACT FROM AUTHOR]

Aquatic animals, such as freshwater turtles, are much dependent on the water bodies where they live. Here we describe the size distribution of a population of Phrynops geoffroanus complex that died after the total drought of the artificial water reservoir where it lived in Caatinga. Amongst the 438 animals we found dead in the Cedro water reservoir, we measured the maximum carapace length of 72 individuals. The population was mainly composed of adult individuals and dead turtles measured in areas that kept water for longer were larger than animals from areas that dried up early. [ABSTRACT FROM AUTHOR]

Background: Piramys auffenbergi was described as an emydine turtle based on a well-preserved skull retrieved from late Miocene deposits exposed on Piram Island, India. The description and figures provided in the original publication are vague and do not support assignment to Emydinae. This taxon has mostly been ignored by subsequent authors. Material and Methods: We reexamine the holotype specimen, provide an extensive description and diagnosis for Piramys auffenbergi, and include this taxon in a global character-taxon matrix for Pleurodira. Results: The presence of a processus trochlearis pterygoidei conclusively shows pleurodiran affinities for Piramys auffenbergi. Inclusion of this taxon in a phylogenetic analysis retrieves it within Stereogenyini closely related to the Asian taxa Shweboemys pilgrimi and Brontochelys gaffneyi. Discussion: Our reexamination of the holotype of Piramys auffenbergi confidently rejects the original assessment of this taxon as an emydine testudinoid and conclusively shows affinities with the pleurodiran clade Stereogenyini instead. Even though most taxa from this lineage are thought to be coastal turtles, all Asian stereogenyines were collected from continental deposits, suggesting a more diverse paleoecology for the group. [ABSTRACT FROM AUTHOR]

Abstract: With aim to report the ontogeny of the osseous elements of the carapace in Peurodiras, 62 embryos and 43 nestlings of Podocnemis expansa were collected and submitted to the clearing and staining technique of bones and cartilages and study of serial histological slices. The carapace has mixed osseous structure of endo and exoskeleton, formed by 8 pairs of costal bones associated with ribs, 7 neural bones associated with neural arches, 11 pairs of peripheral bones, 1 nuchal, 1 pygal and 1 suprapygal. This structure begins its formation in the beginning of stage 16 with the ossification of the periosteal collar of the ribs. With exception of the peripheral bones, the other ones begin their ossification during the embrionary period. In histologic investigation it was found that the costal bones and neural bones have a close relation to the endoskeleton components, originating themselves as intramembranous expansions of the periosteal collar of the ribs and neural arches, respectively. The condensation of the mesenchyme adjacent to the periosteal collar induces the formation of spikes that grow in trabeculae permeated by fibroblasts below the dermis. The nuchal bone also ossifies in an intramembranous way, but does not show direct relation to the endoskeleton. Such information confirms those related to the other Pleurodira, mainly with Podocnemis unifilis, sometimes with conspicuous variations in the chronology of the ossification events. The formation of dermal plates in the carapace of Pleurodira and Criptodira follow the same pattern.

Pleurodires or side-necked turtles are today restricted to freshwater environments of South America, Africa–Madagascar and Australia, but in the past they were distributed much more broadly, being found also on Eurasia, India and North America, and marine environments. Two hypotheses were proposed to explain this distribution; in the first, vicariance would have shaped the current geographical distribution and, in the second, extinctions constrained a previously widespread distribution. Here, we aim to reconstruct pleurodiran biogeographic history and diversification patterns based on a new phylogenetic hypothesis recovered from the analysis of the largest morphological dataset yet compiled for the lineage, testing which biogeographical process prevailed during its evolutionary history. The resulting topology generally agrees with previous hypotheses of the group and shows that most diversification shifts were related to the exploration of new niches, e.g. littoral or marine radiations. In addition, as other turtles, pleurodires do not seem to have been much affected by either the Cretaceous–Palaeogene or the Eocene–Oligocene mass extinctions. The biogeographic analyses highlight the predominance of both anagenetic and cladogenetic dispersal events and support the importance of transoceanic dispersals as a more common driver of area changes than previously thought, agreeing with previous studies with other non-turtle lineages.

A high diversity of land vertebrates is known from the Late Cretaceous deposits of the Bauru Basin, Brazil, including at least five turtle taxa, all belonging to the clade Podocnemidoidae. Some of the richest fossil sites of this basin are in the area of Monte Alto, which yielded several squamate, dinosaur, and crocodyliform taxa. Yet, the single turtle reported so far from this area was only briefly described. Here, we further describe that specimen, a complete but very crushed shell, as well as a partial skull, both found in outcrops of the Adamantina Formation. Comparison of the shell to other podocnemidoid taxa reveals its affinities to Roxochelys wanderleyi, a turtle originally described from that same stratigraphic unit. The comparative description of the skull and its inclusion in a phylogenetic study, supports the proposal of a new taxon, Yuraramirim montealtensis, representing a lineage (Peiropemydidae) so far known only from the Marília Formation of the Bauru Basin and the early Paleocene of Bolivia. The digitally reconstructed endocast and inner ear of the new taxon were also described, as not previously done for a fossil pleurodire. [ABSTRACT FROM AUTHOR]

Bothremydidae is the most abundant and diverse group of turtles in the upper Cretaceous fossil sites of southwestern Europe. Several species a priori recognized as exclusive of the Portuguese, Spanish and French records were defined. The most abundant and best-preserved Spanish collection of pleurodiran turtles from the last Stages of the Upper Cretaceous comes from the fossil site of Lo Hueco (Cuenca Province, Central Spain). The bothremydid Iberoccitanemys convenarum , defined by a single specimen from the Maastrichtian of Haute-Garonne (Southern France), was subsequently recognized as a very abundant form in this Spanish site, corresponding to the only bothremydid so far identified as being part of the diversity of Bothremydidae of both countries. The presence of a second member of Bothremydidae was recognized in Lo Hueco, representing the only evidence of the synchronic and sympatric coexistence of two members of this lineage in a European site. However, very scarce information about this second form from Lo Hueco was available. Thus, its attribution to a new taxon or to a member of Foxemydina previously identified in the Spanish record, or in that of other European regions, could not be evaluated until now. New material from Lo Hueco, not attributable to I. convenarum but to this second larger form, allows its generic and specific identification. Close paleobiogeographical relationships considering the fauna of pleurodiran turtles from Spain and France are recognized thanks to the findings performed in Lo Hueco: not only I. convenarum is known in both countries, but also the French Foxemys mechinorum is identified in Central Spain. [ABSTRACT FROM AUTHOR]

The aim of the present paper is to describe a new species of the genus Cheloniodiplostomum (Digenea, Proterodiplostomidae) in the Hilaire’s toadhead turtle Phrynops hilarii from Argentina and to expand the geographic and host distribution of Cheloniodiplostomum testudinis. Additionally, we present a diagnostic key for Cheloniodiplostomum. [ABSTRACT FROM AUTHOR]

Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2-11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni. [ABSTRACT FROM AUTHOR]

Pseudemydura umbrina is one of the most endangered turtle species in the world, and the imperative for its conservation is its distinctive morphology and relict status among the Chelidae. We use Illumina sequencing to obtain the complete mitogenome for resolving its uncertain phylogenetic position. A novel nuclear paralogue confounded the assembly, and resolution of the authentic mitogenome required further Sanger sequencing. The P. umbrina mitogenome is 16,414 bp comprising 37 genes organized in a conserved pattern for other vertebrates. The nuclear paralogue is 547 bp, 97.8% identity to the corresponding mitochondrial sequence. Particular features of the mitogenome include an nd3 174+1A frameshift, loss of DHC loop in tRNA Ser (AGN), and a light-strand replication initiation site in Wancy region that extends into an adjacent tRNA gene. Phylogenetic analysis showed that P. umbrina is the monotypic sister lineage to the remaining Australasian Chelidae, a lineage probably dating back to the Cretaceous. [ABSTRACT FROM AUTHOR]

The relatively complete and well preserved shell of a turtle, from the middle Cenomanian of Nazaré (Portugal), is studied here. It is recognized as a member of the crown group Pleurodira and, more specifically, of Bothremydidae. Pleurodira are one of the two lineages of modern turtles, their origin being in Gondwana. Pleurodira are very abundant in the uppermost Cretaceous record of Europe. However, this new finding is one of the few occurrences in the lower Upper Cretaceous of Laurasia. A single member of Bothremydidae had so far been identified in Portugal: the late Campanian-early Maastrichtian Rosasia soutoi . It was the only Cretaceous turtle identified in that country both at specific and at generic levels, being exclusive of Portugal. The taxon from Nazaré is identified as Algorachelus peregrinus , this form is also present in the contemporaneous beds in Spain, and is the oldest member of Bothremydidae in Laurasia. Algorachelus peregrinus is confirmed here to be a coastal form, which facilitated its spread. The two oldest known bothremydids from Laurasia, the European A. peregrinus and the North American Paiutemys tibert , are compared for the first time. They are recognized as closely related taxa. This study provides new data allowing a more precisely characterization of the oldest so far known dispersal event of Pleurodira in Laurasia, which was performed by an African lineage of Bothremydidae that reached the east coast of the Atlantic Ocean at least in the middle Cenomanian, and the west region of that Ocean at least in the late Cenomanian. [ABSTRACT FROM AUTHOR]

The Bauru Basin (south-central Brazil) fossils have largely contributed to understand the faunal composition of South American Cretaceous. Among those, several turtle specimens were retrieved from those deposits, all belonging to Podocnemidoidae, the single group known from the Basin. On the other hand, only incomplete shell elements indicate large turtles such as ‘Peirópolis A’. Another shell fragment, a large peripheral plate from the Marília Formation, is described here. Its lack of surface ornamentation, and deep sulci are generally typical for podocnemidoids. The plate exhibits a narrow knob slightly projected onto the pleuro-marginal sulcus, absent in any other Bauru Basin turtle. According to extant and fossil podocnemidoids measures, we estimated this individual reached 1 m of carapace length, exceeding in size all other taxa known from the Basin. This new report reveals a broader size variation among podocnemidoids from the Late Cretaceous of Bauru Basin and a morphological diversity previously unknown for the period, comparable to those of the Amazon Basin today, in which inhabits the largest extant podocnemidoidPodocnemis expansa. Furthermore, the occurrence of such large turtles implies the presence of perennial streams on the northeastern portion of the Bauru Basin during the Maastrichtian and a richer environment than previously thought. [ABSTRACT FROM AUTHOR]

Pan-Pleurodira is one of the two clades of extant turtles (i.e. Testudines). Its crown group, Pleurodira, has a Gondwanan origin being known from the Barremian. Cretaceous turtle fauna of Gondwana was composed almost exclusively of pleurodires. Extant pleurodires live in relatively warm regions, with a geographical distribution restricted to tropical regions that were part of Gondwana. Although pleurodires were originally freshwater forms, some clades have adapted to a nearshore marine lifestyle, which contributed to their dispersal. However, few lineages of Pleurodira reached Laurasian regions and no representatives have so far been described from the pre-Santonian of Laurasia, where the continental and coastal Cretaceous faunas of turtles consist of clades exclusive to this region. A new turtle,Algorachelus peregrinusgen. et sp. nov., is described here from the southern Laurasian Cenomanian site of Algora in Spain. Numerous remains, including a skull and well-preserved postcranial specimens, are attributed to this species. The abundant shell elements, much more numerous than those known in most members of pleurodiran clade Bothremydidae, allow its variability to be studied. The new taxon represents the oldest evidence of the occurrence of Pleurodira in Laurasia, and is the oldest genus of the abundant and diverse Bothremydodda so far described. Factors such as the relatively high Cenomanian temperatures, the adaptation of this Gondwanan clade to coastal environments, and the geographical proximity between the two landmasses may have contributed to its dispersal. This finding shows that the first dispersals of Pleurodira from Gondwana to Laurasia occurred much earlier than previously thought. http://zoobank.org/urn:lsid:zoobank.org:pub:8FD358A5-53BD-4308-828A-AC6802184185 [ABSTRACT FROM PUBLISHER]

This study explores the potential morphological differences between pleurodiran and cryptodiran turtle shells. Pleurodires (Suborder Pleurodira), as suggested by their name, retract their heads into the shell by bending the neck to the side; this is different from cryptodires (Suborder Cryptodira), which withdraw their necks along a sagittal plane. Pleurodires also have evolved a unique pelvic morphology typified by two columnar pelvic elements sutured to both the carapace and plastron; in contrast, the pelvic girdle in cryptodires is loosely connected to the shell. These differences might put very different selective pressures on shell shape in these animals: The different head retraction strategies in the two groups could lead pleurodires to evolve wider and flatter anterior apertures while the differences in pelvic structure might permit the evolution of flatter carapaces (particularly in the posterior carapace) and narrower bridges as compared to cryptodires. We used 3D landmark data to characterize shell shape and used phylomorphospace plots to examine patterns of diversification within pleurodires. We also used analyses of variance to examine morphological differences between the shell shapes of cryptodire and pleurodire turtles. We found significant phylogenetic signal in pleurodire shell shape. Clustering of pleurodires in shape space primarily followed phylogeny, with all major clades occupying distinct regions of shell shape space. Pleurodires overlapped most strongly in shell shape with aquatic cryptodires, both swimmers (including sea turtles) and bottom-walkers (such as chelydrids). Future studies could seek additional support for the hypotheses, through mechanical tests of shell performance, that the mechanism of neck retraction or the presence of columnar pelvic girdles can influence the functional performance of turtle shells. [ABSTRACT FROM AUTHOR]

A new genus and species of panchelid turtle ( Mendozachelys wichmanni gen. et sp. nov.) from the upper Campanian–lower Maastrichtian Loncoche Formation (southern Mendoza Province, Argentina) is described here. This species is represented by only one complete and articulated large specimen (carapace length estimated in 950 mm) that was recovered from tidal flat deposits. A detailed morphological and osteohistological description is made, recognizing autapomorphic characters that allow differentiating this taxon from the rest of extant and extinct panchelids. Osteohistological characters suggest an aquatic to semi-aquatic life style for Mendozachelys wichmanni gen. et sp. nov. Phylogenetic analysis based on morphological data suggested that this new taxon is nested within crown Chelidae. Both phylogenetic signals (morphological and molecular) about the assessment of long-necked chelids monophyly or polyphyly are discussed. [ABSTRACT FROM AUTHOR]