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Published: 10 December 2022
Last updated: 28 January 2023

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1

Diedrich, C., and R. Hirayama. "Turtle remains (Testudines, Chelonioidea) from the Middle Turonian of northwest Germany." Netherlands Journal of Geosciences 82, no. 2 (July 2003): 161–67. http://dx.doi.org/10.1017/s0016774600020710.

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AbstractTurtle 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.
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2

Evers, Serjoscha W., Paul M. Barrett, and Roger B. J. Benson. "Anatomy ofRhinochelys pulchriceps(Protostegidae) and marine adaptation during the early evolution of chelonioids." PeerJ 7 (May 1, 2019): e6811. http://dx.doi.org/10.7717/peerj.6811.

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Knowledge of the early evolution of sea turtles (Chelonioidea) has been limited by conflicting phylogenetic hypotheses resulting from sparse taxon sampling and a superficial understanding of the morphology of key taxa. This limits our understanding of evolutionary adaptation to marine life in turtles, and in amniotes more broadly. One problematic group are the protostegids, Early–Late Cretaceous marine turtles that have been hypothesised to be either stem-cryptodires, stem-chelonioids, or crown-chelonioids. Different phylogenetic hypotheses for protostegids suggest different answers to key questions, including (1) the number of transitions to marine life in turtles, (2) the age of the chelonioid crown-group, and (3) patterns of skeletal evolution during marine adaptation. We present a detailed anatomical study of one of the earliest protostegids,Rhinochelys pulchricepsfrom the early Late Cretaceous of Europe, using high-resolution μCT. We synonymise all previously named European species and document the variation seen among them. A phylogeny of turtles with increased chelonioid taxon sampling and revised postcranial characters is provided, recovering protostegids as stem-chelonioids. Our results imply a mid Early Cretaceous origin of total-group chelonioids and an early Late Cretaceous age for crown-chelonioids, which may inform molecular clock analyses in future. Specialisations of the chelonioid flipper evolved in a stepwise-fashion, with innovations clustered into pulses at the origin of total-group chelonioids, and subsequently among dermochelyids, crown-cheloniids, and gigantic protostegids from the Late Cretaceous.
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3

Kear, Benjamin P., and Michael S. Y. Lee. "A primitive protostegid from Australia and early sea turtle evolution." Biology Letters 2, no. 1 (November 15, 2005): 116–19. http://dx.doi.org/10.1098/rsbl.2005.0406.

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Sea turtles (Chelonioidea) are a prominent group of modern marine reptiles whose early history is poorly understood. Analysis of exceptionally well preserved fossils of Bouliachelys suteri gen. et sp. nov., a large-bodied basal protostegid (primitive chelonioid) from the Early Cretaceous (Albian) of Australia, indicates that early sea turtles were both larger and more diverse than previously thought. The analysis implies at least five distinct sea turtle lineages existed around 100 million years ago. Currently, the postcranially primitive Ctenochelys and Toxochelys are interpreted as crown-group sea turtles closely related to living cheloniids (e.g. Chelonia ); in contrast, the new phylogeny suggests that they are transitional (intermediate stem-taxa) between continental testudines and derived, pelagic chelonioids.
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4

Gentry, Andrew D., Jun A. Ebersole, and Caitlin R. Kiernan. "Asmodochelys parhami , a new fossil marine turtle from the Campanian Demopolis Chalk and the stratigraphic congruence of competing marine turtle phylogenies." Royal Society Open Science 6, no. 12 (December 2019): 191950. http://dx.doi.org/10.1098/rsos.191950.

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Resolving the phylogeny of sea turtles is uniquely challenging given the high potential for the unification of convergent lineages due to systematic homoplasy. Equivocal reconstructions of marine turtle evolution subsequently inhibit efforts to establish fossil calibrations for molecular divergence estimates and prevent the accurate reconciliation of biogeographic or palaeoclimatic data with phylogenetic hypotheses. Here we describe a new genus and species of marine turtle, Asmodochelys parhami , from the Upper Campanian Demopolis Chalk of Alabama and Mississippi, USA represented by three partial shells. Phylogenetic analysis shows that A. parhami belongs to the ctenochelyids, an extinct group that shares characteristics with both pan-chelonioids and pan-cheloniids. In addition to supporting Ctenochelyidae as a sister taxon of Chelonioidea, our analysis places Protostegidae outside of the Chelonioidea crown group and recovers Allopleuron hofmanni as a stem dermochelyid. Gap excess ratio (GER) results indicate a strong stratigraphic congruence of our phylogenetic hypothesis; however, the highest GER value is associated with the phylogenetic hypothesis of marine turtles which excludes Protostegidae from the Cryptodira crown group. Ancestral range estimations derived from our phylogeny imply a European or North American origin of Chelonioidea in the middle-to-late Campanian, approximately 20 Myr earlier than current molecular divergence studies suggest.
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5

Khashman, Adnan, Oyebade Oyedotun, and Fahreddin Sadikoglu. "Intelligent Recognition of Chelonioidea Sea Turtles." Procedia Computer Science 102 (2016): 617–22. http://dx.doi.org/10.1016/j.procs.2016.09.451.

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6

Scavezzoni, Isaure, and Valentin Fischer. "Rhinochelys amaberti Moret (1935), a protostegid turtle from the Early Cretaceous of France." PeerJ 6 (April 10, 2018): e4594. http://dx.doi.org/10.7717/peerj.4594.

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Modern marine turtles (chelonioids) are the remnants of an ancient radiation that roots in the Cretaceous. The oldest members of that radiation are first recorded from the Early Cretaceous and a series of species are known from the Albian-Cenomanian interval, many of which have been allocated to the widespread but poorly defined genus Rhinochelys, possibly concealing the diversity and the evolution of early marine turtles. In order to better understand the radiation of chelonioids, we redescribe the holotype and assess the taxonomy of Rhinochelys amaberti Moret (1935) (UJF-ID.11167) from the Late Albian (Stoliczkaia dispar Zone) of the Vallon de la Fauge (Isère, France). We also make preliminary assessments of the phylogenetic relationships of Chelonioidea using two updated datasets that widely sample Cretaceous taxa, especially Rhinochelys. Rhinochelys amaberti is a valid taxon that is supported by eight autapomorphies; an emended diagnosisis proposed. Our phylogenetic analyses suggest that Rhinochelys could be polyphyletic, but constraining it as a monophyletic entity does not produce trees that are significantly less parsimonious. Moreover, support values and stratigraphic congruence indexes are fairly low for the recovered typologies, suggesting that missing data still strongly affect our understanding of the Cretaceous diversification of sea turtles.
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7

Brinkman, Donald B., and Jiang-Hua Peng. "Ordosemys leios, n.gen., n.sp., a new turtle from the Early Cretaceous of the Ordos Basin, Inner Mongolia." Canadian Journal of Earth Sciences 30, no. 10 (October 1, 1993): 2128–38. http://dx.doi.org/10.1139/e93-184.

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Ordosemys leios, n.gen., n.sp., from the Early Cretaceous Luohandong Formation, Zhidan Group, Ordos Basin, Inner Mongolia, is a primitive aquatic turtle with a reduced, fenestrated plastron. It shares with the members of the Centrocryptodira the presence of well-formed articular surfaces on the cervical and caudal vertebrae. Within the Centrocryptodira, characters of the cervical vertebrae suggest it is more closely related to the Polycryptodira than is the Meiolaniidae. Ordosemys shares with the Chelydridae the presence of two procoelous anterior caudals, but this character may be primitive for the Polycryptodira. Characters of the basicranial region of the braincase shared by Ordosemys and the Chelonioidea support a sister-group relationship between these two taxa, but a sister-group relationship between Ordosemys and the Polycryptodira is more strongly supported by characters shared by the Chelonioidea and other members of the Polycryptodira.
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8

Matzke, Andreas T. "Osteology of the skull of Toxochelys (Testudines, Chelonioidea)." Palaeontographica Abteilung A 288, no. 4-6 (July 6, 2009): 93–150. http://dx.doi.org/10.1127/pala/288/2009/93.

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9

Nicholls, Elizabeth L. "Note on the occurrence of the marine turtle Desmatochelys (Reptilia: Chelonioidea) from the Upper Cretaceous of Vancouver Island." Canadian Journal of Earth Sciences 29, no. 2 (February 1, 1992): 377–80. http://dx.doi.org/10.1139/e92-033.

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An incomplete specimen of Desmatochelys cf. D. lowi (Reptilia: Chelonioidea) from the Trent River Formation (Santonian–Campanian) of the Comox Basin of eastern Vancouver Island is the first documented account of Cretaceous marine vertebrates from the Pacific coast of Canada. It represents both stratigraphic and geographic range extensions for the genus Desmatochelys.
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10

Brinkman, Donald B., Michael Densmore, Márton Rabi, Michael J. Ryan, and David C. Evans. "Marine turtles from the Late Cretaceous of Alberta, Canada." Canadian Journal of Earth Sciences 52, no. 8 (August 2015): 581–89. http://dx.doi.org/10.1139/cjes-2014-0189.

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Previously reported and new specimens of marine turtles from the late Campanian of Alberta, Canada, provide additional information on the diversity and distribution of chelonioid turtles at this time. An articulated carapace from the Bearpaw Formation previously interpreted as Lophochelys niobrarae is considered to be a juvenile of a specifically indeterminate chelonioid and is referred to Lophochelys sp. Isolated neurals and a hyoplastron from nonmarine estuarine deposits in the uppermost beds of the Dinosaur Park Formation are tentatively referred to Lophochelys sp. These specimens suggest that this chelonioid could enter freshwater environments. A new chelonioid, Kimurachelys slobodae gen. et sp. nov., is recognized on the basis of two mandibles and a maxilla from the uppermost beds of the Dinosaur Park Formation of southeastern Alberta. A partial postcranial skeleton of an indeterminate chelonioid from the Bearpaw Formation provides additional evidence that chelonioids of this formation included taxa that were phylogenetically intermediate between chelonioids of the late Santonian and members of the crown group.
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11

Nicholls, Elizabeth L. "New material ofToxochelys latiremisCope, and a revision of the genusToxochelys(Testvoines, Chelonioidea)." Journal of Vertebrate Paleontology 8, no. 2 (June 22, 1988): 181–87. http://dx.doi.org/10.1080/02724634.1988.10011696.

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12

Krahl, Anna. "The locomotory apparatus and paraxial swimming in fossil and living marine reptiles: comparing Nothosauroidea, Plesiosauria, and Chelonioidea." PalZ 95, no. 3 (June 1, 2021): 483–501. http://dx.doi.org/10.1007/s12542-021-00563-w.

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AbstractThe terrestrial origins of the diapsid Sauropterygia and Testudines are uncertain, with the latter being highly controversially discussed to this day. For only 15 Ma, Nothosauroidea lived in shallow-marine seas of the Triassic. Contrastingly, the pelagic Plesiosauria evolved in the Late Triassic, dispersed globally, and inhabited the oceans of the Jurassic and Cretaceous for approximately 135 Ma. Since the Cretaceous (~ 100 Ma), Chelonioidea, the modern sea turtles, have populated the oceans. All three groups evolved aquatic paraxial locomotion. Nothosaurs swam with their foreflippers, supported by the swimming tail. Plesiosaurs are the only tetrapods to have ever evolved four hydrofoil-like flippers. The plesiosaur flipper beat cycle has been debated for nearly two centuries. The different proposed locomotory styles (rowing, rowing-flight, underwater flight) are discussed in this review. A fourth gait that is employed by Carettochelys insculpta, which combines rowing and flying, is introduced. The osteology of the locomotory apparatus of nothosaurs and plesiosaurs is reviewed and compared to that of extant underwater-flying Chelonioidea. In conclusion, underwater flight remains the favoured locomotory style for plesiosaurs. Also, the review reveals that nothosaur locomotion has largely remained unstudied. Further, our understanding of joint morphologies and mobilities of the foreflipper in nothosaurs, plesiosaurs, and even recent sea turtles, and of the hindflipper in plesiosaurs, is very limited. It is crucial to the discussion of locomotion, to find out, if certain limb cycles were even possible, as evidence seems to point to the improbability of a rowing motion because of limited humerus and femur long axis rotation in plesiosaurs.
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13

Nicholls, Elizabeth L., Tim T. Tokaryk, and Len V. Hills. "Cretaceous marine turtles from the Western Interior Seaway of Canada." Canadian Journal of Earth Sciences 27, no. 10 (October 1, 1990): 1288–98. http://dx.doi.org/10.1139/e90-138.

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Late Cretaceous marine turtles are rare in Canada, but specimens are known from three formations: Toxochelys latiremis Cope and Protostega sp. from the Pierre Shale, Pembina Member (lower Campanian); Lophochelys niobrarae Zangerl and Chelonioidea genus indet. from the Bearpaw Formation (upper Campanian); Protostegidae genus indet. and one other taxon from the Niobrara Formation (Coniacian).The Canadian records of the listed taxa constitute the northernmost limits of their known range and may represent their northern limits in the Cretaceous inland sea. Taxonomic diversity and relative abundance of turtles in the Canadian samples are significantly less than in comparable faunas to the south. Cool marine climates may have excluded local nesting and discouraged migrations into northern areas.
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14

Bardet, Nathalie, and Xabier Pereda-Suberbiola. "Las faunas de reptiles marinos del Cretácico final de Europa (margen norte del Tetis mediterráneo)." Spanish Journal of Palaeontology 11, no. 1 (February 25, 2022): 91. http://dx.doi.org/10.7203/sjp.23903.

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Se analizan las faunas de reptiles marinos del Cretácico final (Santoniense a Maastrichtiense) de Europa, en el margen norte del mar de Tetis mediterráneo, desde un punto de vista sistemático y bioestratigráfico. Se establece una correlación entre las principales formaciones y las zonas de belemnites. Las faunas de reptiles marinos de la provincia europea situadas entre los 30° y 40° N de latitud estan dominadas por los mosasaurios y las tortugas Chelonioidea. Los plesiosaurios (elasmosaurios y pliosaurios) son bastante escasos y provienen de las localidades más septentrionales (a partir de 40° N). Los cocodrilos Dyrosauridae y las serpientes Paleophidae no estan representados en el registro fósil europeo. Este modelo de distribución de los reptiles marinos parece estar controlado por los gradientes latitudinales.
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15

Gentry, Andrew D. "Prionochelys matutinaZangerl, 1953 (Testudines: Pan-Cheloniidae) from the Late Cretaceous of the United States and the evolution of epithecal ossifications in marine turtles." PeerJ 6 (November 1, 2018): e5876. http://dx.doi.org/10.7717/peerj.5876.

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BackgroundMany neritic to nearshore species of marine adapted turtle from the Late Cretaceous of North America are thought to represent the stem lineage of Cheloniidae but due to fragmentary holotypes, low total specimen counts, and resultantly incomplete morphological character suites, are routinely placed either within or outside of crown group Chelonioidea leaving their precise cladistic affinities uncertain. Despite this systematic ambiguity, the referral of these species to either the stem of Cheloniidae or Chelonioidea belies the critical importance of these taxa in any investigation into the origins of extant marine turtles. The adequate incorporation of these species into phylogenetic studies requires the formal description of relatively complete specimens, particularly those possessing associated cranial and post-cranial material.MethodsRemarkably complete fossil specimens of several adult and juvenile marine turtles from the Mooreville Chalk and Eutaw Formations (Alabama, USA) are formally described and assigned toPrionochelys matutina. This material provides new information into the anatomy, ontogeny, and cladistic affinities of the species. A phylogenetic hypothesis for Late Cretaceous marine turtles is then generated through the consilience of stratigraphic, morphological, and molecular data.ResultsPhylogenetic analysis placesPrionochelys matutinaon the stem of Cheloniidae as a member of a monophyletic clade with other putative pan-cheloniids, includingCtenochelys stenoporus,Ctenochelys acris,Peritresius martini, andPeritresius ornatus. The members of this clade possess incipient secondary palates, pronounced carapacial and plastral fontanelles at all stages of development, and are characterized by the presence of superficial ossifications at the apices of the neural keel elevations along the dorsal midline of the carapace.DiscussionThe epithecal osteoderms dorsal to the neural series (epineurals) found in Ctenochelyidae are unique among turtles. The presence of epineurals in ctenochelyid turtles shows that epithecal ossifications arose independently in both leatherback (Dermochelyidae) and hard-shelled (Cheloniidae) marine turtles. Whether or not the epineurals of Ctenochelyidae are homologous with the dermal ossicles comprising the carapace ofDermochelys coriacearemains untested however, histological thin sectioning of dermochelyid and ctenochelyd epithecal elements may reveal meaningful information in future studies.
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16

Sterli, Juliana. "Phylogenetic relationships among extinct and extant turtles: the position of Pleurodira and the effects of the fossils on rooting crown-group turtles." Contributions to Zoology 79, no. 3 (September 24, 2010): 93–106. http://dx.doi.org/10.1163/18759866-07903002.

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The origin and evolution of the crown-group of turtles (Cryptodira + Pleurodira) is one of the most interesting topics in turtle evolution, second perhaps only to the phylogenetic position of turtles among amniotes. The present contribution focuses on the former problem, exploring the phylogenetic relationships of extant and extinct turtles based on the most comprehensive phylogenetic dataset of morphological and molecular data analyzed to date. Parsimony analyses were conducted for different partitions of data (molecular and morphological) and for the combined dataset. In the present analysis, separate analyses of the molecular data always retrieve Pleurodira allied to Trionychia. Separate analysis of the morphological dataset, by contrast, depicts a more traditional arrangement of taxa, with Pleurodira as the sister group of Cryptodira, being Chelonioidea the most basal cryptodiran clade. The simultaneous analysis of all available data retrieves all major extant clades as monophyletic, except for Cryptodira given that Pleurodira is retrieved as the sister group of Trionychia. The paraphyly of Cryptodira is an unorthodox result, and is mainly caused by the combination of two factors. First, the molecular signal allies Pleurodira and Trionychia. Second, the morphological data with extinct taxa locates the position of the root of crown-group Testudines in the branch leading to Chelonioidea. This study highlights major but poorly explored topics of turtle evolution: the alternate position of Pleurodira and the root of crown turtles. The diversification of crown turtles is characterized by the presence of long external branches and short internal branches (with low support for the internal nodes separating the major clades of crown turtles), suggesting a rapid radiation of this clade. This rapid radiation is also supported by the fossil record, because soon after the appearance of the oldest crown-group turtles (Middle-Late Jurassic of Asia) the number and diversity of turtles increases remarkably. This evolutionary scenario of a rapid diversification of modern turtles into the major modern lineages is likely the reason for the difficulty in determining the interrelationships and the position of the root of crown-group turtles.
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17

Jones, Marc E. H., Ingmar Werneburg, Neil Curtis, Rod Penrose, Paul O’Higgins, Michael J. Fagan, and Susan E. Evans. "The Head and Neck Anatomy of Sea Turtles (Cryptodira: Chelonioidea) and Skull Shape in Testudines." PLoS ONE 7, no. 11 (November 7, 2012): e47852. http://dx.doi.org/10.1371/journal.pone.0047852.

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18

Suryadi, Indra, and Ariusmedi Ariusmedi. "PENYU DALAM KARYA SENI GRAFIS INTAGLIO PRINT." Serupa The Journal of Art Education 10, no. 4 (December 28, 2021): 307. http://dx.doi.org/10.24036/sr.v9i3.112255.

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Sea turtles (Chelonioidea) can be found in all oceans except for the polar regions. Sea turtles have a pair of front limbs as rower legs which make swimming easier. Althought it stays in the water for the rest of its life, it occasionally has to go on surface of the water to take a breath.Sea turtles, in this artwork aims to visualizes an expression of the writer's anxiety about the endangered turtle population. This artwork made by the intaglio print technique as one of the graphic art techniques. After various observations and long steps of work, these 10 artworks created and displayed namely : 1) Pemangsa, 2) Pencurian telur, 3) Ancaman, 4) Abnormal, 5) Harapan, 6) Terdampar, 7) Memakan plastik, 8) Korban, 9) Impian, 10) Terjerat. This is the result of sea turtles artwork which illustrates the writer's anxiety about the current phenomenon. Besides, this graphic work is expected to be a source of encouragement for other creators.Keywords: Sea Turtles, Graphic Art, Intaglio Print
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19

Cadena, Edwin. "The first South American sandownid turtle from the Lower Cretaceous of Colombia." PeerJ 3 (December 15, 2015): e1431. http://dx.doi.org/10.7717/peerj.1431.

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Sandownids are a group of Early Cretaceous-Paleocene turtles that for several decades have been only known by cranial and very fragmentary postcranial elements. Here I report and describe the most complete sandownid turtle known so far, including articulated skull, lower jaw and postcranial elements, from the Early Cretaceous (upper Barremian-lower Aptian, >120 Ma), Paja Formation, Villa de Leyva town, Colombia. The new Colombian sandownid is defined here asLeyvachelys cipadinew genus, new species and because of its almost identical skull morphology with a previously reported turtle from the Glen Rose Formation, Texas, USA, both are grouped in a single and officially (ICNZ rules) defined taxon. Phylogenetic analysis includingL. cipadisupports once again the monophyly of Sandownidae, as belonging to the large and recently redefined Pan-Chelonioidea clade. The morphology ofL. cipadiindicates that sandownids were not open marine turtles, but instead littoral to shallow marine durophagous dwellers.Leyvachelys cipadinot only constitutes the first record of sandowinds in South America, but also the earliest global record for the group.
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20

Lehman, Thomas M., and Susan L. Tomlinson. "Terlinguachelys fischbecki, a new genus and species of sea turtle (Chelonioidea: Protostegidae) from the Upper Cretaceous of Texas." Journal of Paleontology 78, no. 6 (November 2004): 1163–78. http://dx.doi.org/10.1017/s0022336000043973.

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Remains of a large sea turtle, Terlinguachelys fischbecki n. gen. and sp., were recovered from paralic deposits of the Upper Cretaceous (Campanian) Aguja Formation in Big Bend National Park, Texas. T. fischbecki is a primitive protostegid that retains a constricted humerus, well ossified plastron and costals, prominent retroarticular process on the lower jaw, and long slender femora; however, it has some features, such as a prominent tubercle at the base of the scapular acromion process, found elsewhere only in derived leatherback sea turtles. The unique combination of primitive and derived traits in T. fischbecki illustrates further diversity among Cretaceous sea turtles and another case of parallelism common in sea turtle phylogeny.
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LEHMAN, THOMAS M., and SUSAN L. TOMLINSON. "TERLINGUACHELYS FISCHBECKI, A NEW GENUS AND SPECIES OF SEA TURTLE (CHELONIOIDEA: PROTOSTEGIDAE) FROM THE UPPER CRETACEOUS OF TEXAS." Journal of Paleontology 78, no. 6 (November 2004): 1163–78. http://dx.doi.org/10.1666/0022-3360(2004)078<1163:tfanga>2.0.co;2.

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22

Raselli, Irena. "Comparative cranial morphology of the Late Cretaceous protostegid sea turtle Desmatochelys lowii." PeerJ 6 (December 7, 2018): e5964. http://dx.doi.org/10.7717/peerj.5964.

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Background The phylogenetic placement of Cretaceous marine turtles, especially Protostegidae, is still under debate among paleontologists. Whereas protostegids were traditionally thought to be situated within the clade of recent marine turtles (Chelonioidea), some recent morphological and molecular studies suggest placement along the stem of Cryptodira. The main reason why the evolution of marine turtles is still poorly understood, is in part due to a lack of insights into the cranial anatomy of protostegids. However, a general availability of high-quality fossil material, combined with modern analysis techniques, such as X-ray microtomography, provide ample opportunity to improve this situation. The scope of this study is to help resolve its phylogenetic relationships by providing a detailed description of the external and internal cranial morphology of the extinct protostegid sea turtle Desmatochelys lowii Williston, 1894. Material and Methods This study is based on the well-preserved holotype of Desmatochelys lowii from the Late Cretaceous (middle Cenomanian to early Turonian) Greenhorn Limestone of Jefferson County, Nebraska. The skulls of two recent marine turtles, Eretmochelys imbricata (Linnaeus, 1766) (Cheloniidae) and Dermochelys coriacea Lydekker, 1889 (Dermochelyidae), as well as the snapping turtle Chelydra serpentina (Linnaeus, 1758) (Chelydridae) provide a comparative basis. All skulls were scanned using regular or micro CT scanners and the scans were then processed with the software program Amira to create 3D isosurface models. In total, 81 bones are virtually isolated, figured, and described, including the nature of their contacts. The novel bone contact data is compiled and utilized in a preliminary phenetic study. In addition, an update phylogenetic analysis is conduced that utilizes newly obtained anatomical insights. Results The detailed examination of the morphology of the herein used specimens allowed to explore some features of the skull, to refine the scoring of Desmatochelys lowii in the recent global matrix of turtles, and develop five new characters. The alleged pineal foramen in the type skull of Desmatochelys lowii is shown to be the result of damage. Instead, it appears that the pineal gland only approached the skull surface, as it is in Dermochelys coriacea. Whereas the parasphenoid in confirmed to be absent in hard-shelled sea turtles, ist possible presence in Desmatochelys lowii is unclear. The results of the phenetic study show that Desmatochelys lowii is least similar to the other examined taxa in regards to the nature of its bone contacts, and therefore suggests a placement outside Americhelydia for this protostegid sea turtle. The phylogenetic study results in a placement of Protostegidae along the stem of Chelonioidea, which is a novel position for the group.
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Infante-Rojas, Harvey, Leonardo Marino-Ramirez, and Javier Hernández-Fernández. "Structural analysis of leucine, lysine and tryptophan mitochondrial tRNA of nesting turtles Caretta caretta (Testudines: Chelonioidea) in the Colombian Caribbean." PeerJ 8 (June 18, 2020): e9204. http://dx.doi.org/10.7717/peerj.9204.

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The understanding of the functional properties of mitochondrial transfer RNA (mt tRNAs) depend on the knowledge of its structure. tRNA acts as an interface between polynucleotides and polypeptides thus, they are key molecules in protein biosynthesis. The tRNA molecule has a functional design and, given its importance in the translation of mitochondrial genes, it is plausible that modifications of the structure can affect the synthesis of proteins and the functional properties of the mitochondria. In a previous work, the mitochondrial genome of an individual of the nesting Caretta caretta of the Colombian Caribbean was obtained, where specific mutations were identified in the only tRNALeu (CUN), tRNATrp and tRNALys genes. In order to analyze the effect of these mutations on these three mt tRNAs, the prediction of 2D and 3D structures was performed. Genes were sequenced in 11 nesting loggerhead turtles from the Colombian Caribbean. Two-dimensional structures were inferred using the ARWEN program, and three-dimensional structures were obtained with the RNA Composer 3D program. Two polymorphisms were identified in tRNATrp and another one was located in tRNALys, both specific to C. caretta. The thymine substitution in nucleotide position 14 of tRNATrp could constitute an endemic polymorphism of the nesting colony of the Colombian Caribbean. Two 2D and three 3D patterns were obtained for tRNATrp. In the case of tRNALys and tRNALeu 2D and 3D structures were obtained respectively, which showed compliance to canonical structures, with 4 bp in the D-arm, 4–5 bp in the T-arm, and 5 bp in the anticodon arm. Moderate deviations were found, such as a change in the number of nucleotides, elongation in loops or stems and non-Watson–Crick base pairing: adenine–adenine in stem D of tRNATrp, uracil–uracil and adenine–cytosine in the acceptor arm of the tRNALys and cytosine–cytosine in the anticodon stem of the tRNALeu. In addition, distortions or lack of typical interactions in 3D structures gave them unique characteristics. According to the size of the variable region (4–5 nt), the three analyzed tRNAs belong to class I. The interactions in the three studied tRNAs occur mainly between D loop—variable region, and between spacer bases—variable region, which classifies them as tRNA of typology II. The polymorphisms and structural changes described can, apparently, be post-transcriptionally stabilized. It will be crucial to perform studies at the population and functional levels to elucidate the synthetic pathways affected by these genes. This article analyses for the first time the 1D, 2D and 3D structures of the mitochondrial tRNALys, tRNATrp and tRNALeu in the loggerhead turtle.
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Collareta, Alberto, Rafael Varas-Malca, Giulia Bosio, Mario Urbina, and Giovanni Coletti. "Ghosts of the Holobiont: Borings on a Miocene Turtle Carapace from the Pisco Formation (Peru) as Witnesses of Ancient Symbiosis." Journal of Marine Science and Engineering 11, no. 1 (December 29, 2022): 45. http://dx.doi.org/10.3390/jmse11010045.

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In spite of the widespread occurrence of epibiotic turtle barnacles (Coronuloidea: Chelonibiidae and Platylepadidae) on extant marine turtles (Chelonioidea: Cheloniidae and Dermochelyidae), and although the association between these cirripedes and their chelonian hosts has existed for more than 30 million years, only a few studies have investigated the deep past of this iconic symbiotic relationship on palaeontological grounds. We describe probable platylepadid attachment scars in the form of hemispherical/hemiellipsoidal borings on an Upper Miocene (Tortonian) fragmentary turtle carapace, identified herein as belonging to Cheloniidae, from the Pisco Lagerstätte (East Pisco Basin, southern Peru). When coupled with the available molecular data, this and other similar ichnofossils allow for hypothesising that platylepadid symbionts were hosted by sea turtles as early as in early Oligocene times and became relatively widespread during the subsequent Miocene epoch. Chelonian fossils that preserve evidence of colonisation by platylepadid epibionts in the form of pits on the turtle shell should be regarded as fossil holobionts, i.e., palaeontological witnesses of discrete communal ecological units formed by a basibiont and the associated symbionts (including the epibiota). A greater attention to the bone modifications that may be detected on fossil turtle bones is expected to contribute significantly to the emerging field of palaeosymbiology.
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Lenin, Kanagasabai. "Opposition-based chaotic Henry’s law-soluble gas, hybridization of chelonioidea with anthoathecata and vaporization of liquid optimization algorithms for power loss diminution." Soft Computing 26, no. 4 (January 15, 2022): 1563–85. http://dx.doi.org/10.1007/s00500-021-06710-4.

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Krahl, Anna, and Ulrich Witzel. "Foreflipper and hindflipper muscle reconstructions of Cryptoclidus eurymerus in comparison to functional analogues: introduction of a myological mechanism for flipper twisting." PeerJ 9 (December 15, 2021): e12537. http://dx.doi.org/10.7717/peerj.12537.

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Background Plesiosaurs, diapsid crown-group Sauropterygia, inhabited the oceans from the Late Triassic to the Late Cretaceous. Their most exceptional characteristic are four hydrofoil-like flippers. The question whether plesiosaurs employed their four flippers in underwater flight, rowing flight, or rowing has not been settled yet. Plesiosaur locomotory muscles have been reconstructed in the past, but neither the pelvic muscles nor the distal fore- and hindflipper musculature have been reconstructed entirely. Methods All plesiosaur locomotory muscles were reconstructed in order to find out whether it is possible to identify muscles that are necessary for underwater flight including those that enable flipper rotation and twisting. Flipper twisting has been proven by hydrodynamic studies to be necessary for efficient underwater flight. So, Cryptoclidus eurymerus fore- and hindflipper muscles and ligaments were reconstructed using the extant phylogenetic bracket (Testudines, Crocodylia, and Lepidosauria) and correlated with osteological features and checked for their functionality. Muscle functions were geometrically derived in relation to the glenoid and acetabulum position. Additionally, myology of functionally analogous Chelonioidea, Spheniscidae, Otariinae, and Cetacea is used to extract general myological adaptations of secondary aquatic tetrapods to inform the phylogenetically inferred muscle reconstructions. Results A total of 52 plesiosaur fore- and hindflipper muscles were reconstructed. Amongst these are flipper depressors, elevators, retractors, protractors, and rotators. These muscles enable a fore- and hindflipper downstroke and upstroke, the two sequences that represent an underwater flight flipper beat cycle. Additionally, other muscles were capable of twisting fore- and hindflippers along their length axis during down- and upstroke accordingly. A combination of these muscles that actively aid in flipper twisting and intermetacarpal/intermetatarsal and metacarpodigital/metatarsodigital ligament systems, that passively engage the successive digits, could have accomplished fore-and hindflipper length axis twisting in plesiosaurs that is essential for underwater flight. Furthermore, five muscles that could possibly actively adjust the flipper profiles for efficient underwater flight were found, too.
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Carthy, Raymond R. "An Owner's Manual for the Chelonioidae." Conservation Biology 20, no. 1 (January 23, 2006): 259–60. http://dx.doi.org/10.1111/j.1523-1739.2006.00357_4.x.

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Myers, Troy. "Osteological Morphometrics of Australian Chelonioid Turtles." Zoological Science 24, no. 10 (October 2007): 1012–27. http://dx.doi.org/10.2108/zsj.24.1012.

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Hirayama, Ren. "Phylogenetic systematics of chelonioid sea turtles." Island Arc 3, no. 4 (December 1994): 270–84. http://dx.doi.org/10.1111/j.1440-1738.1994.tb00116.x.

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Kapuścińska, Agnieszka, and Marcin Machalski. "Upper Albian chelonioid turtles from Poland." Geobios 48, no. 5 (September 2015): 385–95. http://dx.doi.org/10.1016/j.geobios.2015.07.002.

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Bardet, Nathalie. "Maastrichtian marine reptiles of the Mediterranean Tethys: a palaeobiogeographical approach." Bulletin de la Société Géologique de France 183, no. 6 (December 1, 2012): 573–96. http://dx.doi.org/10.2113/gssgfbull.183.6.573.

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AbstractA global comparison of coeval Maastrichtian marine reptiles (squamates, plesiosaurs, chelonians and crocodyliformes) of Europe, New Jersey, northwestern Africa and Middle-East has been performed. More than twenty outcrops and fifty species (half of them being mosasaurids) have been recorded. PEA and Cluster Analysis have been performed using part of this database and have revealed that marine reptile faunas (especially the mosasaurid ones) from the Mediterranean Tethys are clearly segregated into two different palaeobiogeographical provinces: 1) The northern Tethys margin province (New Jersey and Europe), located around palaeolatitudes 30-40°N and developping into warm-temperate environments, is dominated by mosasaurid squamates and chelonioid chelonians; it is characterized by the mosasaurid association of Mosasaurus hoffmanni and Prognathodon sectorius. 2) The southern Tethys margin province (Brazil and the Arabo-African domain), located between palaeolatitudes 20°N-20°S and developping into intertropical environments, is dominated by mosasaurid squamates and bothremydid chelonians; it is characterized by the mosasaurid association of Globidens phosphaticus as well as by Halisaurus arambourgi and Platecarpus (?) ptychodon (Arabo-African domain). These faunal differences are interpreted as revealing palaeoecological preferences probably linked to differences in palaeolatitudinal gradients and/or to palaeocurrents.On a palaeoecological point on view and concerning mosasaurids, the mosasaurines (Prognathodon, Mosasaurus, Globidens and Carinodens) prevail on both margins but with different species. The ichthyophageous plioplatecarpines Plioplatecarpus (Northern margin) and Platecarpus (?) ptychodon (Southern margin) characterise respectively each margin. The halisaurine Halisaurus is present on both margins but with different species. Of importance, the tylosaurines remain currently unknown on the southern Tethys margin and are restricted to higher palaeolatitudes. Chelonians (bothremydids and chelonioids) are respective of each margin, which probably indicates lower dispersal capabilities compared to mosasaurids. The relative scarcity of plesiosaurs and crocodyliformes could be linked to different ecological preferences. The noteworthy crocodyliforme diversity increase in the Palaeogene is probably linked to mosasaurid extinction during the biological crisis of the K/Pg boundary.
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Grant-Mackie, J. A., J. Hill, and B. J. Gill. "Two Eocene chelonioid turtles from Northland, New Zealand." New Zealand Journal of Geology and Geophysics 54, no. 2 (June 2011): 181–94. http://dx.doi.org/10.1080/00288306.2010.520325.

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Sarmento, Martha, Andrea Chaves, Mónica Retamosa, Clemens Ruepert, Ricardo Jiménez, and Kinndle Blanco. "Análisis descriptivo de las condiciones de conservación de un sitio de forrajeo de la tortuga verde del Pacífico (Chelonia mydas agassizii, Testudines: Chelonioidea) en el Golfo Dulce, Costa Rica; se toma como base el estado de salud de la tortuga y el hallazgo de plaguicidas en el ambiente." Revista Ciencias Veterinarias 33, no. 2 (April 4, 2016): 81. http://dx.doi.org/10.15359/rcv.33-2.3.

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El desarrollo de estrategias de manejo, que permitan la conservación de las tortugas marinas y del Golfo Dulce, requiere de insumos relacionados con la condición actual de la salud de estas poblaciones. Diversos estudios han relacionado la manifestación clínica de enfermedades como la fibropapilomatosis (FP) en tortugas marinas con estresores ambientales y actividades antropogénicas, los cuales pueden ocasionar la presencia de contaminantes y el deterioro ambiental de zonas de forrajeo y anidación. Al considerar este ligamen, se desarrolló este estudio, el cual constituye una caracterización ambiental de un sitio de forrajeo, a partir del estado de la salud de la tortuga verde del pacífico (<span class="CharOverride-20">Chelonia mydas agassizii</span>) y de las condiciones ambientales de este sitio (un sitio de forrajeo) en el Golfo Dulce, Costa Rica, entre el 2010 y 2012. Para ello, se determinó el estado físico de 77 tortugas, la presencia de FP y la detección molecular de CFPHV. Se analizó el uso de suelo y la densidad poblacional cercana a la zona de estudio; así como la presencia de plaguicidas en muestras de sedimento marino, agua y pasto marino; también, en sangre de 10 tortugas muestreadas. Entre los resultados obtenidos, destaca el hecho de que la condición general del golfo es conservada, únicamente con la presencia de cultivos de arroz cercanos a la zona y un sector en crecimiento poblacional importante. Se determinó la presencia de un herbicida, clomazona, y el buen estado de salud de los quelonios estudiados, en apariencia libres de FP. Sin embargo, se detectó, molecularmente, el posible agente causal de FP en 26% (20) de los individuos muestreados. Con esta investigación se logró reconocer, al Golfo Dulce, como un importante sitio de forrajeo para la tortuga verde del Pacífico, el cual cuenta con las condiciones adecuadas para su conservación y protección.
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de Lapparent de Broin, France, Nathalie Bardet, Mbarek Amaghzaz, and Saïd Meslouh. "A strange new chelonioid turtle from the Latest Cretaceous Phosphates of Morocco." Comptes Rendus Palevol 13, no. 2 (February 2014): 87–95. http://dx.doi.org/10.1016/j.crpv.2013.07.008.

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Lewya, Ze'ev, and Eugene S. Gaffneyb. "First record of a possible chelonioid sea turtle from the Upper Campanian of southern Israel." Israel Journal of Earth Sciences 54, no. 1 (January 1, 2005): 55–58. http://dx.doi.org/10.1560/l1c8-kurt-nb6f-0gaj.

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KEAR, BENJAMIN P., and GRAHAM E. BUDD. "New perspectives on ancient marine reptiles." Geological Magazine 151, no. 1 (October 25, 2013): 5–6. http://dx.doi.org/10.1017/s0016756813000873.

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Amniotes first invaded saline lagoons and coastal seaways towards the end of the Palaeozoic (Early Permian, ~ 280 Ma: Piñeiro et al. 2012), but by the dawn of the Mesozoic (Early–Middle Triassic, ~ 250–235 Ma: Rieppel, 2002; McGowan & Motani, 2003) they had achieved a diversity of specialized body-forms requisite for an obligate oceanic lifestyle. Such an explosive ecomorphological radiation paved the way for amniote dominance of large-bodied aquatic carnivore/omnivore niches over the next 185 Ma, with some lineages (e.g. dyrosaurid crocodylomorphs and bothremydid turtles: Gaffney, Tong & Meylan, 2006; Barbosa, Kellner & Sales Viana, 2008) even persisting on into the Palaeogene (until ~ 50 Ma), and diversifying (i.e. chelonioid sea turtles: Hirayama, 1997) alongside emergent marine mammals through the Neogene (from ~ 23 Ma) and up until today.
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Milan, Jesper, Bent E. K. Lindow, and Bodil W. Lauridsen. "Bite traces in a turtle carapace fragment from the middle Danian (Lower Paleocene) bryozoan limestone, Faxe, Denmark." Bulletin of the Geological Society of Denmark 59 (September 30, 2011): 61–67. http://dx.doi.org/10.37570/bgsd-2011-59-07.

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A fragment of a turtle carapace from the Middle Danian bryozoan limestone at the Faxe quarry, eastern Denmark, is identified as a partial costal plate from the carapace of a chelonioid turtle. The fragment bears traces of three separate acts of predation or scavenging. Two circular bite traces Nihilichnus nihilicus Mikuláš et al. 2006, 4 mm in diameter, situated 2.5 cm apart, are interpreted as crocodylian. Groups of parallel scrapes, Machichnus bohemicus Mikuláš et al. 2006, 4–5 mm long and 0.5 mm wide, are interpreted as bite traces from sharks. Small circular traces, ~1 mm in diameter, found either alone or in a row of three, are either from sharks or fish. This is the first record of turtles from the Danian bryozoan limestone exposed in Faxe quarry, and thus represents an important addition to the Danian vertebrate fauna of Denmark.
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Falbo, Agustín D., and Federico L. Agnolin. "First record of a chelonioid sea turtle (Testudines, Pan-Cheloniidae) from the late Miocene of Argentina." Alcheringa: An Australasian Journal of Palaeontology 44, no. 3 (July 2, 2020): 475–80. http://dx.doi.org/10.1080/03115518.2020.1814411.

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39

Danise, Silvia, and Nicholas D. Higgs. "Bone-eating Osedax worms lived on Mesozoic marine reptile deadfalls." Biology Letters 11, no. 4 (April 2015): 20150072. http://dx.doi.org/10.1098/rsbl.2015.0072.

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We report fossil traces of Osedax , a genus of siboglinid annelids that consume the skeletons of sunken vertebrates on the ocean floor, from early-Late Cretaceous (approx. 100 Myr) plesiosaur and sea turtle bones. Although plesiosaurs went extinct at the end-Cretaceous mass extinction (66 Myr), chelonioids survived the event and diversified, and thus provided sustenance for Osedax in the 20 Myr gap preceding the radiation of cetaceans, their main modern food source. This finding shows that marine reptile carcasses, before whales, played a key role in the evolution and dispersal of Osedax and confirms that its generalist ability of colonizing different vertebrate substrates, like fishes and marine birds, besides whale bones, is an ancestral trait. A Cretaceous age for unequivocal Osedax trace fossils also dates back to the Mesozoic the origin of the entire siboglinid family, which includes chemosynthetic tubeworms living at hydrothermal vents and seeps, contrary to phylogenetic estimations of a Late Mesozoic–Cenozoic origin (approx. 50–100 Myr).
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Bardet, Nathalie, Nour-Eddine Jalil, France de Lapparent de Broin, Damien Germain, Olivier Lambert, and Mbarek Amaghzaz. "A Giant Chelonioid Turtle from the Late Cretaceous of Morocco with a Suction Feeding Apparatus Unique among Tetrapods." PLoS ONE 8, no. 7 (July 11, 2013): e63586. http://dx.doi.org/10.1371/journal.pone.0063586.

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Parham, James F., and Nicholas D. Pyenson. "New sea turtle from the Miocene of Peru and the iterative evolution of feeding ecomorphologies since the Cretaceous." Journal of Paleontology 84, no. 2 (March 2010): 231–47. http://dx.doi.org/10.1666/09-077r.1.

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The seven species of extant sea turtles show a diversity of diets and feeding specializations. Some of these species represent distinctive ecomorphs that can be recognized by osteological characters and therefore can be identified in fossil taxa. Specifically, modifications to the feeding apparatus for shearing or crushing (durophagy) are easily recognizable in the cranium and jaw. New sea turtle fossils from the Miocene of Peru, described as a new genus and species (Pacifichelys urbinain. gen. and n. sp.), correspond to the durophagous ecomorph. This new taxon is closely related to a recently described sea turtle from the middle Miocene of California, USA (Pacifichelys hutchisonin. comb.), providing additional information on the osteological characters of this lineage. A phylogenetic analysis ofPacifichelysand other pan-chelonioid sea turtle lineages shows that at least seven lineages independently evolved feeding specialized for shearing or crushing. the iterative evolution of these morphologies is plausibly linked to ecological factors such as the development of seagrass communities and the opening of niches through extinction that occurred from the Cretaceous to the Miocene.
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Evers, Serjoscha W., and Walter G. Joyce. "A re-description of Sandownia harrisi (Testudinata: Sandownidae) from the Aptian of the Isle of Wight based on computed tomography scans." Royal Society Open Science 7, no. 2 (February 2020): 191936. http://dx.doi.org/10.1098/rsos.191936.

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Sandownidae is an enigmatic group of Cretaceous–Paleogene turtles with highly derived cranial anatomy. Although sandownid monophyly is not debated, relationships with other turtles remain unclear. Sandownids have been recovered in significantly different parts of the turtle tree: as stem-turtles, stem-cryptodires and stem-chelonioid sea turtles. Latest phylogenetic studies find sandownids as the sister-group of the Late Jurassic thalassochelydians and as stem-turtles. Here, we provide a detailed study of the cranial and mandibular anatomy of Sandownia harrisi from the Aptian of the Isle of Wight, based on high resolution computed tomography scanning of the holotype. Our results confirm a high number of anatomical similarities with thalassochelydians and particularly Solnhofia parsonsi , which is interpreted as an early member of the sandownid lineage. Sandownids + Solnhofia show many cranial modifications related to the secondary palate and a durophagous diet. Sandownia is additionally highly derived in features related to its arterial circulation and neuroanatomy, including the endosseous labyrinth. Our results imply rapid morphological evolution during the early history of sandownids. Sandownids likely evolved in central Europe from thalassochelydian ancestors during the Late Jurassic. The durophagous diet of sandownids possibly facilitated their survival of the Cretaceous/Paleogene mass extinction.
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Cicimurri, David J., James L. Knight, Jean M. Self-Trail, and Sandy M. Ebersole. "Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA." Journal of Paleontology 90, no. 1 (January 2016): 147–53. http://dx.doi.org/10.1017/jpa.2016.16.

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AbstractHeavily tuberculated glyptosaur osteoderms were collected in an active limestone quarry in northern Berkeley County, South Carolina. The osteoderms are part of a highly diverse late Paleocene vertebrate assemblage that consists of marine, terrestrial, fluvial, and/or brackish water taxa, including chondrichthyan and osteichthyan fish, turtles (chelonioid, trionychid, pelomedusid, emydid), crocodilians, palaeopheid snakes, and a mammal. Calcareous nannofossils indicate that the fossiliferous deposit accumulated within subzone NP9a of the Thanetian Stage (late Paleocene, upper part of Clarkforkian North American Land Mammal Age [NALMA]) and is therefore temporally equivalent to the Chicora Member of the Williamsburg Formation. The composition of the paleofauna indicates that the fossiliferous deposit accumulated in a marginal marine setting that was influenced by fluvial processes (estuarine or deltaic).The discovery of South Carolina osteoderms is significant because they expand the late Paleocene geographic range of glyptosaurines eastward from the US midcontinent to the Atlantic Coastal Plain and provide one of the few North American records of these lizards inhabiting coastal habitats. This discovery also brings to light a possibility that post-Paleocene expansion of this group into Europe occurred via northeastward migration along the Atlantic coast of North America.
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BARDET, N., H. CAPPETTA, X. PEREDA SUBERBIOLA, M. MOUTY, A. K. AL MALEH, A. M. AHMAD, O. KHRATA, and N. GANNOUM. "The marine vertebrate faunas from the Late Cretaceous phosphates of Syria." Geological Magazine 137, no. 3 (May 2000): 269–90. http://dx.doi.org/10.1017/s0016756800003988.

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Marine vertebrate faunas from the latest Cretaceous phosphates of the Palmyrides Chain of Syria are described for the first time. Recent fieldwork in the phosphatic deposits of the Palmyra area (mines of Charquieh and Khneifiss, outcrops of Bardeh, Soukkari and Soukhneh) have yielded a rich and diversified assemblage of marine vertebrates, including more than 50 species of chondrichthyes, osteichthyes, squamates, chelonians, plesiosaurians and crocodilians. Selachians are the most abundant and diverse component of the faunas and are represented by at least 34 species of both sharks and rays. Actinopterygians include representatives of six families, the most common being the enchodontids. Squamates are known by six mosasaurid species and an indeterminate varanoid. Chelonians are represented by at least two bothremydids and two chelonioids. Finally, elasmosaurid plesiosaurs and indeterminate crocodilians are also present in the fossil assemblages. The difference in faunal composition observed between the sites is interpreted as being due to palaeoecological preferences related to the Hamad Uplift palaeostructure. The marine vertebrate faunas of Syria show close affinities with those of the latest Cretaceous phosphatic deposits of North Africa and the Middle East and are typical of the southern Tethyan realm. From a biostratigraphical point of view, the selachians are the only suitable material to provide elements of an answer to the long debated question of the age of the Syrian Senonian phosphates. They suggest an Early Maastrichtian age for most of the phosphates of the Palmyrides Chain.
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Chatterji, Ray M., Christy A. Hipsley, Emma Sherratt, Mark N. Hutchinson, and Marc E. H. Jones. "Ontogenetic allometry underlies trophic diversity in sea turtles (Chelonioidea)." Evolutionary Ecology, March 5, 2022. http://dx.doi.org/10.1007/s10682-022-10162-z.

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AbstractDespite only comprising seven species, extant sea turtles (Cheloniidae and Dermochelyidae) display great ecological diversity, with most species inhabiting a unique dietary niche as adults. This adult diversity is remarkable given that all species share the same dietary niche as juveniles. These ontogenetic shifts in diet, as well as a dramatic increase in body size, make sea turtles an excellent group to examine how morphological diversity arises by allometric processes and life habit specialisation. Using three-dimensional geometric morphometrics, we characterise ontogenetic allometry in the skulls of all seven species and evaluate variation in the context of phylogenetic history and diet. Among the sample, the olive ridley (Lepidochelys olivacea) has a seemingly average sea turtle skull shape and generalised diet, whereas the green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) show different extremes of snout shape associated with their modes of food gathering (grazing vs. grasping, respectively). Our ontogenetic findings corroborate previous suggestions that the skull of the leatherback (Dermochelys coriacea) is paedomorphic, having similar skull proportions to hatchlings of other sea turtle species and retaining a hatchling-like diet of relatively soft bodied organisms. The flatback sea turtle (Natator depressus) shows a similar but less extreme pattern. By contrast, the loggerhead sea turtle (Caretta caretta) shows a peramorphic signal associated with increased jaw muscle volumes that allow predation on hard shelled prey. The Kemp’s ridley (Lepidochelys kempii) has a peramorphic skull shape compared to its sister species the olive ridley, and a diet that includes harder prey items such as crabs. We suggest that diet may be a significant factor in driving skull shape differences among species. Although the small number of species limits statistical power, differences among skull shape, size, and diet are consistent with the hypothesis that shifts in allometric trajectory facilitated diversification in skull shape as observed in an increasing number of vertebrate groups.
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Chatterji, Ray M., Mark N. Hutchinson, and Marc E. H. Jones. "Redescription of the skull of the Australian flatback sea turtle, Natator depressus, provides new morphological evidence for phylogenetic relationships among sea turtles (Chelonioidea)." Zoological Journal of the Linnean Society, July 21, 2020. http://dx.doi.org/10.1093/zoolinnean/zlaa071.

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Abstract Chelonioidea (sea turtles) are a group where available morphological evidence for crown-group relationships are incongruent with those established using molecular data. However, morphological surveys of crown-group taxa tend to focus on a recurring subset of the extant species. The Australian flatback sea turtle, Natator depressus, is often excluded from comparisons and it is the most poorly known of the seven extant species of Chelonioidea. Previous descriptions of its skull morphology are limited and conflict. Here we describe three skulls of adult N. depressus and re-examine the phylogenetic relationships according to morphological character data. Using X-ray micro Computed Tomography we describe internal structures of the braincase and identify new phylogenetically informative characters not previously reported. Phylogenetic analysis using a Bayesian approach strongly supports a sister-group relationship between Chelonia mydas and N. depressus, a topology that was not supported by previous analyses of morphological data but one that matches the topology supported by analysis of molecular data. Our results highlight the general need to sample the morphological anatomy of crown-group taxa more thoroughly before concluding that morphological and molecular evidence are incongruous.
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Ramos, Elisa Karen da Silva, Lucas Freitas, and Mariana F. Nery. "The role of selection in the evolution of marine turtles mitogenomes." Scientific Reports 10, no. 1 (October 12, 2020). http://dx.doi.org/10.1038/s41598-020-73874-8.

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Abstract Sea turtles are the only extant chelonian representatives that inhabit the marine environment. One key to successful colonization of this habitat is the adaptation to different energetic demands. Such energetic requirement is intrinsically related to the mitochondrial ability to generate energy through oxidative phosphorylation (OXPHOS) process. Here, we estimated Testudines phylogenetic relationships from 90 complete chelonian mitochondrial genomes and tested the adaptive evolution of 13 mitochondrial protein-coding genes of sea turtles to determine how natural selection shaped mitochondrial genes of the Chelonioidea clade. Complete mitogenomes showed strong support and resolution, differing at the position of the Chelonioidea clade in comparison to the turtle phylogeny based on nuclear genomic data. Codon models retrieved a relatively increased dN/dS (ω) on three OXPHOS genes for sea turtle lineages. Also, we found evidence of positive selection on at least three codon positions, encoded by NADH dehydrogenase genes (ND4 and ND5). The accelerated evolutionary rates found for sea turtles on COX2, ND1 and CYTB and the molecular footprints of positive selection found on ND4 and ND5 genes may be related to mitochondrial molecular adaptation to stress likely resulted from a more active lifestyle in sea turtles. Our study provides insight into the adaptive evolution of the mtDNA genome in sea turtles and its implications for the molecular mechanism of oxidative phosphorylation.
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48

Abu El-Kheir, Gebely, Mohamed AbdelGawad, and Walid Kassab. "First known gigantic sea turtle (Testudines: Pan-Chelonioidea) in the Maastrichtian deposits in Egypt." Acta Palaeontologica Polonica 66 (2021). http://dx.doi.org/10.4202/app.00849.2020.

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49

Castillo-Visa, Oscar, Àngel H. Luján, Àngel Galobart, and Albert Sellés. "A gigantic bizarre marine turtle (Testudines: Chelonioidea) from the Middle Campanian (Late Cretaceous) of South-western Europe." Scientific Reports 12, no. 1 (November 17, 2022). http://dx.doi.org/10.1038/s41598-022-22619-w.

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AbstractMarine turtles were common in the subtropical Upper Cretaceous epi-continental seas that once washed the coasts of the ancient European archipelago. But unlike its contemporaneous faunas from North America, in Europe no taxon surpassed the 1.5 m shell-length. Here, the remains of a new large marine turtle, Leviathanochelys aenigmatica gen. et sp. nov., from the Middle Campanian of the Southern Pyrenees are described. Anatomical and histological evidence concur in identifying the specimen as a basal chelonioid. The new taxon autapomorphically differs from other marine turtles by possessing an additional process on the anteromedial side of the pelvis, and an acetabulum directed strongly ventrally. Based on the pelvis size, it is likely that Leviathanochelys was as large as Archelon, thus becoming one of the largest marine turtles found to ever exist. The large body size of the new taxon could have evolved as a response to the unique habitat conditions of the European Cretaceous archipelago seas. The presence of the accessory pubic process further suggests the occurrence of an additional insertion point of the Musculus rectus abdominis, which together with the paleohistologic evidences support the hypothesis that the new taxon had an open marine pelagic lifestyle.
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50

De La Garza, Randolph Glenn, Henrik Madsen, Peter Sjövall, Frank Osbӕck, Wenxia Zheng, Martin Jarenmark, Mary H. Schweitzer, et al. "An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes." Scientific Reports 12, no. 1 (December 31, 2022). http://dx.doi.org/10.1038/s41598-022-26941-1.

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AbstractThe transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid—unlike its scaly living descendants—combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle.
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