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Choristoderes are freshwater diapsid reptiles that are distributed through Laurasia in Jurassic–Miocene deposits. The group shows great diversity in the Early Cretaceous of Asia, with all recognized morphotypes recorded from that region. However, there is then a substantial gap in the Asian record until choristoderes are reported from the Paleocene of Kazakhstan. This gap has raised questions as to whether the group became extinct in Asia during the Late Cretaceous, with subsequent reinvasion from either North America or Europe. Here we report the discovery of vertebrae attributable to Choristodera indet. from the lower Upper Cretaceous (Turonian) of the Tamagawa Formation, Kuji City, Iwate Prefecture, Japan. This is the first record of Choristodera from the Upper Cretaceous of Asia, and may imply that the group persisted in this region from the Jurassic to the Paleocene. The challenge for the future will be to recover a more complete record of Choristodera in the Upper Cretaceous of Asia.

A partial crocodylian skull was found among the paleontological collection at the Archaeological Museum, Waseda University in Honjo-shi, Saitama Prefecture. Following a bibliographical survey, this was verified as a specimen reported by Tokunaga as the first known crocodile from Taiwan but then regarded as lost due to World War II. Molten glass debris is attached to the specimen, suggesting that it had been subject to air raids during World War II in May 1945, most likely at the Waseda University campus. Based on its largest seventh maxillary alveoli and the prominent lateral expansion towards the posterior direction, this specimen was identified as Toyotamaphimeia sp.; up to now a single species under this genus has been reported. The discovery demonstrates that this crocodylian genus once had a wide geographical distribution during the Pleistocene.

金沢大学国際基幹教育院 GS教育系, We report a Late Cretaceous chemosynthetic community fueled by decomposing basal leatherback sea turtle on the ocean floor in the western Pacific. The fossil association representing this community has been recovered from the matrix of a concretion containing a single carapace of Mesodermochelys sp. from Late Cretaceous outer shelf to upper slope deposit of northern Hokkaido, Japan. The carapace displays boreholes most likely performed by boring bivalves, and is associated with molluscan shells, mainly Provanna cf. nakagawensis and Thyasira tanabei. Since this association is similar to fauna already known from Late Cretaceous hydrocarbon seeps, sunken wood, and plesiosaur-falls in Hokkaido, it is suggested that all types of chemosynthesis-based communities in the Late Cretaceous of western Pacific may have belonged to the same regional pool of animals and were not yet fully differentiated into three independent types of communities as it is known today. This finding also indicates that the sulfophilic stage of the vertebrate-fall communities was supported not only by plesiosaur carcasses, which were previously reported, but also by sea turtle carcasses. It highlights the possibility of surviving vertebrate-fall communities through the end-Cretaceous mass extinction event on carcasses of sea turtles which are the only large marine vertebrates surviving this event. Copyright © 2017 R.G. Jenkins et al.

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

Although Neogene crocodylians were well documented from Indo-Pakistan, few fossils were known from Southeast Asia, precluding the understanding of their evolutionary and biogeographic history. Here...

Dental fossils of an indeterminate small cervoid (Ruminantia, Artiodactyla, Mammalia) from the lower Miocene Koura Formation of southwestern Japan are described. The examined specimens of Cervoidea fam., gen. et sp. indet. consist of selenodont lower molars with plesiomorphic characteristics of early cervoids: a strong external postprotocristid (or Palaeomeryx-fold), a deep groove on the lingual wall of the internal postmetacristid, and opening posterior cristids between the postentocristid and the posthypocristid. The lower molars are similar in shape and size with those of Miocene Cervidae rather than Moschidae or Palaeomerycidae because the present specimens are comparable to those of Dicrocerus tokunagai, which is one of the lower/ middle Miocene cervids from northeastern Japan, and D. grangeri from the middle Miocene of China. The lower Miocene Nakamura Formation (ca. 19 Ma) of central Japan also yielded a small cervoid species sharing the lower molar characteristics with Cervoidea fam., ge...

An incomplete specimen assigned to the genus Neurankylus sp. was collected from Coniacian deposits of the Frontier Formation of Montana (USA). The material consists of anterior plastron, a costal plate and neural plate fragment, and several undetermined skeletal elements. The identification is based on the relatively large size of the specimens, scute elements joining along the mid-line of the plastron with the intergulars reaching the humerals, and complete fusion of the sutures. The specimen represents the first baenid turtle reported from non-marine Frontier Formation deposits and is particularly relevant for understanding stratigraphical and paleogeographical distribution of the Family Baenide. This will have important implications for phylogenetic studies and paleoenvironmental interpretation of non-marine Frontier Formation deposits of south-western Montana.

Manouria oyamai, an extinct, endemic testudinid turtle known from the upper Pleistocene of the Ryukyu Archipelago, southwestern Japan, has been reviewed on the basis of new specimens. The new specimens consist of a skull, as well as the first records of the epiplastron and the pelvis, all of which were found in a late Pleistocene fissure-filling deposit on Okinawajima Island, the Central Ryukyus, Japan. The present material provided four new informative morphological characters for M. oyamai: the anterior epiplastral projection, the epiplastra lacking extensive overhanging lip, the wide and fan-shaped iliac blade, and the wide ischiadic plate. The results of morphological comparisons and phylogenetic analysis indicated that M. oyamai is sister to M. emys (occurring in Bangladesh, eastern India, Myanmar, Thailand, the Malay Peninsula, Sumatra, and Borneo), and that M. impressa (in southern China, Laos, Malaysia, Myanmar, Thailand, and Vietnam) is the basal-most taxon within Manouria. In addition, the extremely thin carapace observed in M. oyamai, which had been cited as one of three diagnostic characters of this species as well as a feature thought indicative of insular adaptation, is also present in M. impressa within this genus. The present observation therefore indicates that this character is not always attributable to insular adaptation. The results of this study along with the current paleogeographic hypothesis of the Ryukyu Archipelago suggest that M. oyamai had differentiated from an extinct ancestral species shared with M. emys on the eastern margin of Asian continent not later than the early Pleistocene. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Takahashi, A., R. Hirayama, and H. Otsuka. 2018. Systematic revision of Manouria oyamai (Testudines, Testudinidae), based on new material from the Upper Pleistocene of Okinawajima Island, the Ryukyu Archipelago, Japan, and its paleogeographic implications. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1427594.

Adocus sengokuensis sp. nov. is described on the basis of disarticulated shell elements (nuchal, first peripherals, left fourth peripheral, left second costal, left hyoplastron, and right hypoplastron) collected from a lacustrine mudstone of the Lower Cretaceous Sengoku Formation, Kanmon Group in Miyawaka City, Fukuoka Prefecture, Japan. A. sengokuensis is characterized by its small size with a carapace estimated at only 29 cm long, a trapezoidal cervical scale greater in width than length, and a narrow lateral projection of the first pleu- ral scale of the fourth peripheral. Small size and wide cervical scale suggest that this new species is the most basal taxon of the genus Adocus.

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 trionyc...

Among living turtles, highly terrestrial or highly aquatic modes of life are likely to have developed from a plesiomorphic semi-aquatic one. A taxonomically comprehensive data set of turtle humeri was examined to ascertain if adaptation to an aquatic or a terrestrial lifestyle affects the general internal bone structure. Three-dimensional and virtual cross-sections were obtained from computed microtomography to compare humeral changes among the various lifestyles – terrestrial, semi-aquatic and aquatic – focusing on the degree of resorption of periosteal bone. Regardless of lifestyle, the humeri of the 52 turtles examined lacked a large open medullary cavity, and only one or a few small cavity(ies) or intertrabecular spaces were found near the growth centre. Semi-aquatic and aquatic turtles display the highest and lowest median values of humeral compactness, respectively, suggesting that limb-bone lightening is acquired both in highly terrestrial and in highly aquatic turtles. The broad overlap in compactness values between the lifestyles and the lack of tubular structure in all turtles, however, suggest that selection pressure of skeletal lightening in terrestrial turtles is not high enough to cause a tubular structure, possibly because of the rather passive mode of locomotion in terrestrial turtles. This overlap also suggests that the humeral compactness could not be used alone to provide an indication of lifestyle in turtles. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112, 719–734.

This paper is devoted to the description and revision of material of Cretaceous soft-shelled turtles (Trionychidae) of Mongolia. It includes the description of seven trionychid species, six of which are new, and two new genera: the cyclanorbine Nemegtemys conflata gen. et sp. nov. from the Nemegt Formation (Maastrichtian), and the trionychines Gobiapalone breviplastra gen. et sp. nov. from the Nemegt and Barungoyot (Campanian) formations, G. orlovi from the Baynshire Formation (Cenomanian–Santonian), ‘Trionyx’ baynshirensis sp. nov. from the Baynshire Formation, ‘T.’ gilbentuensis sp. nov. from the Nemegt Formation, ‘T.’ gobiensis sp. nov. from the Nemegt Formation, and ‘T.’ shiluutulensis sp. nov. from an unknown formation (Campanian). In addition, one shell from the ?Baynshire Formation of Khermin Tsav is assigned to Gobiapalone sp. The type material of Amyda menneri is considered to be Trionychidae indet. and Amyda menneri to be a nomen dubium. Finally, we revise other available materials of Cretaceous...

Cretaceous fish fossils are reported from Malaysia for the first time. They were found with dinosaur and turtle remains in nonmarine sediments in the interior of Pahang State, Peninsular Ma...

A well preserved skull of Puppigerus camperi (Testudines: Cryptodira: Cheloniidae) is reported from the Ypresian (Early Eocene) phosphate deposits of the Ouled Abdoun basin, Morocco. This discovery adds an additional element to the rich turtle assemblages hitherto known in the Ouled Abdoun basin, suggesting further close relationships with the Paleogene sea turtle fauna from northwestern Europe.

We describe the tooth of a fossil beaver (Castoridae, Rodentia) discovered in the lower Miocene Koura Formation of Shimane Prefecture, western Japan. The specimen is an isolated, unworn left lower third molar that can be assigned to a large castorid, Youngofiber. To determine the taxonomic classification based on the internal enamel patterns of the tooth, we reconstructed those patterns using a three-dimensional image by X-ray peripheral quantitative computed tomography (pQCT). The obtained enamel patterns indicate that the M3 of Youngofiber is characterized by a transversely elongated proparafossettid and simple synclinids running obliquely and parallel. Moreover, the present specimen retains a well developed mesostriid extending up to half the lingual height of the crown. This characteristic is shared with another castorid specimen from the lower Miocene Nojima Group in Nagasaki Prefecture, suggesting a close relationship between Koura and Nojima beavers.

Forearc basin deposits of the Yezo Group (Matsu-moto, 95 ; Okada, 982), Hokkaido, Northern Japan, yield abundant fossiliferous calcareous concretions. In addition to numerous ammonoids and inoceramids, these concretions contain various vertebrates, including teleosts, mosasaurids, elasmosaurs, both marine and ter-restrial turtles (Hirayama and Chitoku, 996; Hirayama and Hikida, 998; Hirayama

EnglishA new species of Argillochelys (Testudines: Cryptodira: Cheloniidae), A. africana n. sp. is described on the basis of three skulls and a lower jaw from the Lower Tertiary beds of the Ouled Abdoun phosphate basin, Morocco. It differs from A. cuneiceps, A. antiqua and A. athersuchi essentially in the frontal well retracted from the orbital margin, with a broad prefrontal/postorbital contact, a more developed secondary palate, and the anterior part of the lower jaw more dorsoventrally flattened, with a wider triturating surface and a longer symphysis, without lingual ridge. This is the first record of Argillochelys from Africa. francaisUne nouvelle espece d'Argillochelys (Testudines, Cryptodira, Cheloniidae), A. africana n. sp., est decrite a partir de trois crânes et une mandibule provenant du Paleogene du bassin phosphate des Ouled Abdoun au Maroc. Elle differe d'A. cuneiceps, A. antiqua et A. athersuchi essentiellement par le frontal bien exclu du bord de l'orbite, un long contact prefrontal/postorbitaire, un palais secondaire plus developpe ; la partie anterieure de la mandibule plus aplatie dorsoventralement, avec une surface triturante plus large et une symphyse plus longue, sans crete linguale. C'est le premier Argillochelys decouvert en Afrique.

Background. Moroccan phosphates bed includes fossils of Sauropterygia, Testudines and mosasaurs from the latest Cretaceous (Maastrichitian) to Eocene. Family Bothremydidae (Podocnemidoidea), an extinct side-necked turtle group, has broad diversity in cranial morphology as shown by the genus Bothremys (Bothremydini). This genus is known from the Cretaceous and Paleogene of North America, Europe, Africa and middle east Asia, uniquely characterized by a pair of pits on the triturating surface of upper and lower jaws. Hitherto, four species have been recognized in Bothremys; B. cooki, B. kellyi, B. maghrebiana, and B. arabicus. Compared to the diversity of cranial morphology, little difference is known in the shell morphology in bothremydids. Also little is known about the limb morphology of bothremydini turtles, because of poor association of skull and postcranial skeleton. A new excellently preserved specimen of Bothremys is reported from the Upper Cretaceous of Morocco. Methods. The WSILS-RHg519 specimen stored in Waseda University is a large bothremydid skull associated with lower jaw and several postcranial elements including left humerus and peripherals. Results. The pair of pits on the triturating surfaces of upper and lower jaws in WSILSRHg519 specimen is a distinct autoapomorphic characters of the genus Bothremys. With the skull width 171mm, B. arabicus from the Santonian age of Jordan had been the largest species of genus Bothremys. The WSILS-RHg519 reaches the skull width 220mm and would be the largest member of Bothremys. Also, comparing the bone composition of the ventral surface of skull of the WSILS-RHg519 specimen to all other known Bothremys, the palatine-pterygoid contacts and pterygoid-pterygoid contact are quite unique. The left humerus is associated with the skull, partly damaged. The distal end of humerus is wide and the shaft is nearly straight, showing the first morphological evidence of aquatic/marine adaptation different from that of Chedighaii, the sister taxon of Bothremys. Discussion. The marine habitat of bothremydid turtles had been roughly discussed on the basis of the association of shallow marine animals such as shark teeth. Morphological evidence has not suggested yet partly because of the difficulty of bothremydid taxonomy which is just based on the cranial morphology. The WSILS-RHg519 specimen will hopefully shed light on the mysterious habitats of bothremydid turtles.

Background. The genus Megalochelys is the largest known testudinid (family Testudnidae) found from the upper Miocene to lower Pleistocene of India to Indonesian Islands. The maximum length of the shell in this genus has been estimated as up to about 2 m long based on a specimen from the lower Pleistocene of Java Island, Indonesia. Recently, joint paleontological expeditions of Japan and Myanmar led by M. Takai have unearthed abundant fossils of this genus from the Neogene since 2003. These materials shed new light on this unique gigantic tortoise. Methods. All materials of Megalochelys were found from the Lower Irrawaddy Beds in poor preservation except for one nearly complete shell. The shell lengths from the fragmentary materials were estimated by using those of medium to large–sized testudinids. Results. Postcranial materials, including twenty-five epiplastra, one cervical vertebra, appendicular skeletons, and one nearly complete shell (about 180 cm long) have been discovered from the Lower Irrawaddy Beds in narrow area near Pauk Township. They are associated with terrestrial mammals such as Stegodon, suggesting that the age of the fossil bearing beds are attributed to the late Miocene to the early Pliocene. Of these, the epiplastra in two morphological states appear to be derived from sexual dimorphism of this genus as seen in several testudinids and noted previously by second author on the relevant materials. A huge distal portion of the humerus (ca. 31 cm long) suggests that its original length was about 75 cm. Discussion. A nearly complete shell is about 180 cm long, although this seems a rather young male individual of Megalochelys based on its rather slender epiplastral morphology, which is nearly as large as given estimation of the maximum shell length from Java material. On the other hand, the largest humerus, estimated as 75 cm in original length, suggests its shell was about 270 cm long. This estimation seems to be supported by other isolated materials such as the nuchal plate, largest epiplastron, and the pectoral girdle. Hitherto, Stupendemys geographica (from the Pliocene of Venezuela) and Archelon ischyros (from the Lower Cretaceous of North America) were regarded as largest known turtles with about 220 cm long shell. However, Megalochelys from Myanmar involves much larger specimens, suggesting this is a true largest known turtle.

Background. The Trionychoidea were dominant turtles in the Late Cretaceous of Asia and North America. Although Early Cretaceous trionychoids are quite important to reveal their origin and the early evolution, their fossil records are very poor so far. The Lower Cretaceous Kitadani Formation of the Tetori Group is one of the most productive dinosaur-bearing beds of Japan, and has yielded a lot of turtle remains. Trionychid, adocid, and nanhsiungchelyid were published as the oldest records by Hirayama (2002). Herein, we report new information about trionychid and adocid turtles from the Kitadani Formation. Methods. We examined and morphologically described more than 700 materials (mostly isolated shell fragments) from the Kitadani Formation (late Barremian to Aptian) of the Tetori Group in Katsuyama City, Fukui Prefecture, central Japan. All specimens have been collected in the paleontological excavations by Fukui Prefectural Dinosaur Museum since 1988. Results. The turtle fauna consists of four trionychoid taxa and two other eucryptodires. About 80 % are assigned to the Trionychoidea including a trionychid, two taxa of adocids, and a nanhsiungchelyid. Shell and skeletal assemblages of a soft-shelled turtle (FPDM-V9487, 9489) were newly discovered. These have the following synapomorphies as the Trionychidae; vermiculated shell sculpturing, loss of scale sulci, lack of peripheral bones, reduction of plastron, no osseous bridge between carapace and plastron. Furthermore, a reduction of eighth costal, and an indistinct sculpture and callosity on the hypoplastron are common characters in Perochelys, Gobiapalone, and Apalonina. The Adocidae, an extinct semi-aquatic turtle, is the most dominant among turtles in this locality and is composed of two different taxa. Nearly complete shell materials of Adocus sp. have been recovered based on hundreds of fragmentary shell materials and the newly collected shell assemblage of one individual (FPDM-V9173). Another adocid, gen. et sp. indet., is newly recognized on the basis of costals, peripherals, and a hypoplastron. This adocid is distinguished from Adocus sp. by the possession of the marginal scales limited within peripherals, and thinner shells. Discussion. Trionychoids from the Kitadani Formation were composed of dominant families in the Late Cretaceous of Asia and North America. Trionychoids from underlying Kuwajima and Akaiwa formations (Hauterivian to Barremian) of the Tetori Group are quite different. More primitive trionychoids such as “Trionychoidea indet.” and Kappachelys okurai have been unearthed from these formations. This stratigraphical succession suggests that morphological and paleoecological diversification among trionychoid turtles began during the Barremian or Aptian in East Asia. Fossil turtles from the Tetori Group could shed light on the early evolution of trionychoid families.

千葉県袖ケ浦市吉野田の下総層群清川層からイシガメ科に属する2種類の淡水生カメ類, ハナガメ属の化石種Ocadia sp.と小型のヤベイシガメMauremys yabei が確認された. ハナガメ属はほぼ完全な骨格が発見され, またヤベイシガメは2個の保存良好な甲羅が知られている. いずれも日本固有の化石種と考えられ, 第四紀におけるイシガメ類の多様性の大きさを示唆している. 特にハナガメ属の発見は, 当時の古気候の推定に関して再考察をうながすものとして注目される.

千葉県吉野田の下総層群清川層は, 約20万年前の古動植物群を産する化石密集層で知られるが, この動物群の一部が現在の中国揚子江河口域以南の亜熱帯種に類似するのに対し, 植物群は関東地方北部の冷温帯を示唆するなど, 互いに共存しえないほどの古気温推定上のずれを与える問題が生じていた. この問題点を説明するために, 本稿では清川層の花粉群組成を調べるとともに, 同時代の記録として過去43万年間の琵琶湖花粉層序を参照した. また, 房総半島と揚子江河口域の現在の気温状態を比較した. さらに, 地球軌道要素の変動に基づく日射量変動の電算結果を検討した. 結果として, MIS7に対し気温年較差の増大を仮定し, 吉野田動物群の一部が夏の気温に, 植物群がおもに冬の気温に規制されていたとするならば, 両者のずれが整合的に説明されうることを述べた. 年間総熱量の反映としての年平均気温は, 年較差増大を仮定するならば, 現在よりやや低温が要求される.

調査地点は千葉県袖ヶ浦市吉野田で,中部更新統下総層群清川層の露頭である.最近,調査地点において,シカ,カメ,ナウマンゾウなど多数の陸生脊椎動物化石や淡水生貝類化石および植物化石などが発見された.これらの化石を含む地層は河川の氾濫原堆積相(厚さ約1m)で,大きく分けて下位よりA,B,Cの3つの堆積ユニットが認められる.ユニットAは植物片を多く含む塊状粗粒シルト層からなる.ユニットBは淘汰の悪い泥質砂層からなり,木片や陸生脊椎動物の骨片・歯が密集する.この泥質砂層には砂層がレンズ状に複数挾まれ,平行層理や級化層理,粗粒デューンなどが認められる.ユニットCの下部は塊状シルト層で,上部はシルト層と極細粒～細粒砂層との砂泥互層からなる.このユニット中には,原地性を示すカメ化石や淡水生貝類化石などがみられる.これらの堆積相と化石群から,ユニットA～Bは河川の増水時に氾濫原に侵入してきた洪水堆積物で,自然堤防や堤防決壊堆積(クレバススプレイ)などを形成していたと考えられる.ユニットCは,その後,氾濫原に形成された湖沼の泥底とそこに氾濫時に流入した砂層の堆積物より構成される.

An extinct tortoise known from the uppermost Pleistocene of the Ryukyu Islands is described as the new species, Manouria oyamai (Testudines: Testudinidae) based on the skull, lower jaw and some postcranial elements. The specimens of M. oyamai were newly collected from the latest Pleistocene fissure deposits on Okinawa and Tokunoshima Islands, Ryukyu Islands, Japan. This is the first fossil record of Manouria sensu stricto. Phylogenetic analysis shows that Manouria sensu stricto, comprising M. emys, M. impressa and M. oyamai, is monophyletic. Manouria oyamai flourished in the Central and South Ryukyus until the Late Pleistocene and became extinct there, along with other endemic terrestrial vertebrates, in the latest Pleistocene.

Osteopygis emarginatus Cope 1868 is described from the Lower Tertiary of the Ouled Abdoun phosphate basin, Morocco, on the basis of skulls and lower jaws. Osteopygis is a cosmopolitan turtle that had a wide geographical distribution during the Late Cretaceous and Paleocene. Osteopygis emarginatus is a very conservative species which crossed the Cretaceous/Tertiary boundary without major changes.

Turtle remains ascribed to the family Cheloniidae (Testudines, Cryptodira, Chelonioidea), collected from the lamarcki zone (Middle Turonian) at Wüllen (NW Germany) are described. The material consists of a right humerus, a scapula, a complete costalia, and costalia fragments of a single individual with the humerus indicating a primitive cheloniid of the ‘toxochelyid grade’. The present material, as well as previously recorded chelonioid humeri from the Cenomanian and Turonian of Germany illustrate a progressive diversification of chelonioids during the early Late Cretaceous.

Phylogenetic relationships of the genus Cuora sensu lato (Cuora sensu stricto and Cistoclemmys) and other testudinoid genera were inferred from variations in 882 base positions of mitochondrial 12S and 16S rRNA genes. Results yielded a robust support to the monophyly of a group (Cuora group) consisting of Cuora sensu lato and the monotypic Pyxidea. Within the Cuora group, the continental Cuora (sensu stricto) and the two subspecies of Ci. flavomarginata constituted two well-supported monophyletic groups. Distinctly small interspecific genetic distances in the former groups suggested that in the continent speciations in Cuora took place much later than the primary divergences in the Cuora group, or speciations in other related genera, such as Mauremys. Our analyses failed to provide a substantial support to the monophyly of any other combinations of taxa within the Cuora group, including Cuora in broad and strict senses, and Cistoclemmys as consisting of Ci. galbinifrons and Ci. flavomarginata. Besides these, our results also suggested the non-monophyly for the Batagurinae and the Geoemydinae, and sister relationships of the Bataguridae with Testudinidae rather than with the Emydidae.

The early Cretaceous Santana Formation exposed on the Chapada do Araripe in Ceara State, northeastern Brazil, has yielded remains of a side-necked turtle, Cearachelys placidoi, new genus and species. Cearachelys is based on two skeletons, each consisting of articulated shell, associated skull, and postcrania in varying degrees of completeness. Cearachelys is a pelomedusoid pleurodire belonging to the family Bothremydidae Baur, 1891, based on these bothremydid characters: (1) precolumellar fossa absent, (2) occipital condyle consisting only of exoccipitals, (3) foramen stapedio-temporale anteriorly facing, and (4) exoccipital contacts quadrate. Within the Bothremydidae, Cearachelys is best resolved as the sister group of Bothremys, Rosasia, Foxemys, Zolhafah, and Polysternon. Cearachelys differs from the other two pleurodires in the Santana Formation in the bothremydid characters listed above and in having a quadrate-basioccipital contact, a prootic completely covered in ventral view, and a high l...

Monophyly of the batagurid subfamily Geoemydinae was evaluated, and phylogenetic relationships within the subfamily were inferred on the basis of 35 morphological characters. Two approaches, parsimony analysis using the branch and bound algorithm, and neighbor joining clustering of an absolute distance matrix, were used. The results of these analyses yielded phylograms that were almost identical in branching topology, and poorly supported the monophyly of Geoemydinae. This subfamily thus seems to be a metataxon, most likely consisting of the sister group of Batagurinae (Geoemyda group) and a more primitive stock of Bataguridae (Mauremys group). The latter accommodates Mauremys and Sacalia and its monophyly is not well supported. The former consists of the remaining ten geoemydine genera united by two synapomorphies-absence or reduction of the quadratojugal, and posteriorly short-sided anterior neurals. Relationships revealed by our analyses necessitate some changes in the generic classification of Geoemydinae. First of all, Cistoclemmys Gray, 1863 (type species: Ci. flavomarginata, often synonymized to Cuora Gray, 1855 (type species: Cu. amboinensis), is shown to be a valid genus closely related to Pyxidea and Geoemyda rather than to Cuora (sensu stricto). Rhinoclemmys Fitzinger, 1835 (type species: R. punctularia) is shown to be polyphyletic, and Chelopus Cope, 1870 (type species: C. rubida), is resurrected to accommodate R. rubida and R. annulata. The plastral hinge seems to have evolved three times in the Bataguridae-in the Cyclemys-Notochelys clade, Cuora (sensu stricto), and the Cistoclemmys-Pyxidea clade.

Reptiles constitute a primarily terrestrial assemblage, but several groups returned to the marine environment after the first appearance of reptiles in the late Palaeozoic era1. Successful diversification of the chelonioid sea turtles, particularly during the Cretaceous period, was perhaps one of the most important events in the history of turtles (and marine reptiles)2,3,4. The fossil record of chelonioids before the Late Cretaceous has been poorly documented. Here I report the discovery of an exceptionally well-preserved skeleton of the oldest known chelonioid, from the Early Cretaceous stage (about 110 million years before the present)5,6,7 of eastern Brazil. This specimen represents a new taxon, extending the history of chelonioids by 10 million years, and it sheds new light on the early evolution of the group. The limb of the specimen is a relatively primitive paddle, which still possesses movable digits as in freshwater turtles. However, the skull is specialized in the manner of later chelonioids, with large interorbital foramina that are indicative of huge lachrymal salt glands surrounding the eyes8,9. This discovery supports the idea that the establishment of the salt-excreting system, and the occupation of a marine habitat, may have preceded the formation of rigid paddles in the history of chelonioids.

Kappachelys okurai gen. et sp. nov. is named and described based on two isolated carapacial elements (right seventh costal and left seventh peripheral) from the Lower Cretaceous (?upper Neocomian) Akaiwa Formation of west-central Honshu, Japan. Kappachelys is a small turtle (shell length ~10 cm) that exhibits a unique combination of three features: coarse and deep vermiculate sculpture on carpace; no scute sulci; and well-developed peripherals. The form of the sculpture and lack of scute sulci both suggest affinities with the Trionychidae (soft-shelled turtles), whereas the plesiomorphic retention of well-developed peripherals indicates Kappachelys lies outside the Trionychidae. Given this combination of primitive and derived features, we interpret Kappechelys as a stem trionychid. In the same region of Japan, the overlying Lower Cretaceous (Aptian) Kitadani Formation contains some of the oldest known, unequivocal trionychid fossils. Based on its slightly older age, similar geographical distribution, and more primitive shell morphology, Kappachelys could be ancestral to the trionychids of the Kitadani Formation.

Chelonioid sea turtles (Order Testudinata; Superfamily Chelonioidea) first appear in the early Cretaceous (Aptian-Albian). Their long fossil record is excellent compared to most marine tetrapods. Nonetheless, there has been no inclusive attempt to provide an analysis of cladistic relationships among this group. In this paper, the following chelonioid classification is proposed, based on 76 characters among 20 fossil and six living well- represented genera: 1Family Cheloniidae (Coniacian to Recent); Toxochelys, Ctenochelys, Osteopygis, Erquelinnesia, Allopleuron, Argillochelys, Puppigerus, Eochelone, Syllomus, Natator, Eretmochelys, Chelonia, Caretta, Lepidochelys 2Family Protostegidae (Aptian to Maastrichtian?); ‘Santana new protostegid’,Rhinochelys, Notochelone, Desmatochelys, Chelosphargis, Protostega, Archelon 3Family Dermochelyidae (Santonian? to Recent); Corsochelys, ‘HMG new dermo-chelyid’, Eosphargis, Psephophorus, Dermochelys.

ispartof: Journal of African Studies vol:4 pages:31-47 status: published

Publisher Summary This chapter discusses distribution and diversity of Cretaceous chelonioids. The Cretaceous Chelonioidea, which includes at least 22 valid genera, is divided into the three monophyletic families—Cheloniidae, Protostegidae, and Dermochelyidae. The cheloniids are well diversified and abundant in the Late Cretaceous of North America and Western Europe, whereas they are absent from the Japanese Cretaceous. The Protostegidae and Dermochelyidae are considered to be more closely related to each other than either is to the cheloniids. They possess a very elongated coracoid, a pelvic girdle with a huge lateral process of the pubis, and a very long plastron. The skull of protostegids may be modified to feed on hard-shelled animals, judging from the extensive contact between pterygoid and quadrate, and the strong processus trochlearis oticum as seen in the living batagurid Malayemys, which is a typical molluscivorous freshwater turtle. The protostegids were cosmopolitan as were the dominant chelonioids from the Aptian to the Turonian; however, they drastically declined and became extinct during the Maastrichtian. The Mesozoic dermochelyids were dominant only in the Late Cretaceous of Japan. It has been suggested that most Mesozoic sea turtles are endemic, and, cosmopolitan chelonioid species are quite rare.

A new geoemydid turtle, Ocadia tanegashimensis (Testudines: Geoemydidae) is described on the basis of a relatively well–preserved shell from the lower middle Miocene of Tanegashima Island, Kagoshima Prefecture, southwestern Japan. This species is clearly distinguished from two congeneric species (extant O . sinensis and O . nipponica from the middle Pleistocene of eastern Japan) due to the presence of the following character states: length of the entoplastron as long as the interhyoplastral suture, the costals dovetailed with one another in outline, the third pleural overlapping only the sixth and seventh peripherals. The present study suggests that the initial intrageneric diversification of Ocadia began not later than the early Miocene in eastern Asia.

Chelonian eggshell fossils from the Lower Cretaceous Kuwajima Formation of the Tetori Group are described. The eggs were originally spherical or ellipsoidal in shape. The eggshells consist of a single layer of spherulitic shell units composed of needle-like crystallites originating from a nucleation center. This corresponds to modern rigid-shelled chelonian eggs. The eggshell fragments are commonly found buried together and are known from deposits of subaerial environments, such as vegetated swamps. In contrast, the vast majority of turtle remains are known primarily from nearby shallow lake deposits, indicating that they are aquatic; no terrestrial turtles are known from this formation. These taphonomic settings suggest that the eggs were laid on land by lacustrine turtles in a process still apparent today.