Walter Joyce

Université de Fribourg · Department of Geosciences

Depending on taxonomic opinion, between four and five turtle species are well attested for the Middle Eocene Messel Pit formation of Germany. Here, we describe specimen SMF ME-3495 from the Messel collection of the Senckenberg Museum in Frankfurt, which unambiguously corresponds to an additional turtle species. The specimen consists of a partial an...

The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This is in part due to the rarity of undeformed skulls of definitive early stem chelonioids. In this work, we redescribe the holotype of Nichollsemys baieri using µCT scans and segmentations of the skull. This fossil is the best 3D preserved skull of any Campanian sea turtl...

Hutchemys rememdium is a poorly understood softshell turtle (Trionychidae) from the mid Paleocene of the Williston Basin of North America previously known only from postcranial remains. A particularly rich collection of previously undescribed material from the Tiffanian 4 North American Land Mammal Age (NALMA) of North Dakota is here pre-sented con...

Kinosternon is the most speciose genus of extant turtles, with 22 currently recognized species, distributed across large parts of the Americas. Most species have small distributions, but K. leucostomum and K. scorpioides range from Mexico to South America. Previous studies have found discordance between mitochondrial and nuclear phylogenies in some...

Inferring palaeoecology for fossils is a key interest of palaeobiology. For groups with extant representatives, correlations of aspects of body shape with ecology can provide important insights to understanding extinct members of lineages. The origin and ancestral ecology of turtles is debated and various shell or limb proportions have been reporte...

The osteology, neuroanatomy, and musculature are known for most primary clades of turtles (i.e., “families”), but knowledge is still lacking for one particular clade, the Carettochelyidae. Carettochelyids are represented by only one living taxon, the pig‐nosed turtle Carettochelys insculpta. Here, we use micro‐computed tomography of osteological an...

Allaeochelys libyca is a carettochelyid turtle from the Middle Miocene of Libya. The species is the only valid carettochelyid taxon recovered from Africa and was named based on fragmentary material that includes a partial cranium and isolated shell remains. The description of the holotype cranium was limited to external aspects, and micro-computed...

Denazinemys nodosa is a Late Cretaceous representative of the North American turtle clade Baenidae diagnosed, among others, by a shell surface texture consisting of raised welts. We provide a detailed description of a partial skeleton from the late Campanian Kaiparowits Formation of Utah, USA, including bone-by-bone analysis of its cranium based on...

Early Cretaceous (late Barremian – early Aptian) fissure fill deposits near Balve, North Rhine Westphalia, Germany, have yielded a rich continental vertebrate fauna over the course of the last two decades. More than 250 fragmentary specimens, including more than 150 osteoderms (i.e., granicones), represent the late Early Cretaceous helochelydrid He...

Unlabelled: Trionychid (softshell) turtles have a peculiar bauplan, which includes shell reductions and cranial elongation. Despite a rich fossil record dating back to the Early Cretaceous, the evolutionary origin of the trionychid bauplan is poorly understood, as even old fossils show great anatomical similarities to extant species. Documenting s...

We describe the skull of the Early Cretaceous (Aptian-Albian) baenid turtle Trinitichelys hiatti using micro-computed tomography to provide new insights into the cranial anatomy of basal baenids and into the evolution of paracryptodires. We show that the validity of Trinitichelys hiatti vs Arundelemys dardeni still holds true, that the most basal k...

The labyrinth of the vertebrate inner ear is a sensory system that governs the perception of head rotations. Central hypotheses predict that labyrinth shape and size are related to ecological adaptations, but this is under debate and has rarely been tested outside of mammals. We analyze the evolution of labyrinth morphology and its ecological drive...

A number of helochelydrid turtle shell remains were recovered over the course of the 19th century from mid‐Cretaceous sediments throughout Southern England, including the poorly figured and described types of Trachydermochelys phlyctaenus from the Cambridge Greensand of Cambridgeshire, Plastremys lata from the Upper Greensand of the Isle of Wight,...

A series of small-sized fossil turtles were collected from Beckles' Pit, Durlston Bay, Dorset, United Kingdom in 1856 from a sediment package referable to the Early Cretaceous (Berriasian) Purbeck Group. The two primary accounts that previously documented these turtles concluded that they represent the juveniles of the coeval early pleurosternid Pl...

Snapping turtles (Pan‐Chelydridae) play an important role in modern ecosystems throughout North America, but their fossil record is notably poor. We here describe a new species of fossil pan‐chelydrid, Chelydropsis aubasi, from the Middle Eocene (MP15, Bartonian) of Chéry‐Chartreuve, Department of Aisne, France, based on a series of fragments that...

Lakotemys australodakotensis is an Early Cretaceous paracryptodire known from two shells and a skull from the Lakota Formation of South Dakota, USA. Along with the Early Cretaceous Arundelemys dardeni and the poorly known Trinitichelys hiatti, Lakotemys australodakotensis is generally retrieved as an early branching baenid, but more insights into t...

We study the Late Jurassic (Tithonian) turtle Uluops uluops using micro-computed tomography scans to investigate the cranial anatomy of paracryptodires, and provide new insights into the evolution of the internal carotid artery and facial nerve systems, as well as the phylogenetic relationships of this group. We demonstrate the presence of a canali...

The geoemydid turtles of the Eocoene Messel Pit Quarry of Hesse, Germany, are part of a rich Western European fossil record of testudinoids. Originally referred to as “ Ocadia” kehreri and “ Ocadia” messeliana , their systematic relationships remain unclear. A previous study proposed that a majority of the Western European geoemydids, including the...

Late Jurassic deposits across Europe have yielded a rich fauna of extinct turtles. Although many of these turtles are recovered from marine deposits, it is unclear which of these taxa are habitually marine and which may be riverine species washed into nearby basins, as adaptations to open marine conditions are yet to be found. Two new fossils from...

Arundelemys dardeni is an Early Cretaceous paracryptodire known from a single, incomplete, but generally well-preserved skull. Phylogenetic hypotheses of paracryptodires often find Arundelemys dardeni as an early branching baenid. As such, it has a central role in understanding the early evolution of the successful clade Baenidae, which survived th...

Werneburg & Joyce. 2021. Cranial turtle CT scans. MorphoSource, Project 353832: Naomichelys speciosa, Pelodiscus sinensis, Emydura subglobosa, Emys orbicularis, Malaclemys terrapin, Kinixys erosa, Peltocephalus dumerilianus, Carettochelys insculpta, Psammobates tentorius, Malacochersus tornieri, Dermatemys mawii, Chelonoidis sp., Testudo marginata,...

The Maevarano Formation in northwestern Madagascar has yielded a series of exceptional fossils over the course of the last three decades that provide important insights into the evolution of insular ecosystems during the latest Cretaceous (Maastrichtian). We here describe a new genus and species of pelomedusoid turtle from this formation, Sahonache...

Over the last 25 years, researchers, mostly paleontologists, have developed a system of rank-free, phylogenetically defined names for the primary clades of turtles. As these names are not considered established by the PhyloCode, the newly created nomenclatural system that governs the naming of clades, we take the opportunity to convert the vast maj...

The cranial circulation and innervation systems of turtles have been studied for more than two centuries and extensively used to understand turtle systematics. Although a significant number of studies related to these structures exists, a broader comprehension of variation across the tree has been hindered by poor sampling and a lack of synthetic s...

Turtles are a successful clade of reptiles that originated in the Late Triassic. The group adapted during its evolution to different types of environments, ranging from dry land to ponds, rivers, and the open ocean, and survived all Mesozoic and Cenozoic extinction events. The body of turtles is characterized by a shell, which has been hypothesized...

Pleurosternon bullockii is a turtle from the Early Cretaceous of Europe known from numerous postcranial remains. Only one skull has so far been referred to the species. Pleurosternon bullockii belongs to a group of turtles called pleurosternids, which is thought to include several poorly known taxa from the Late Jurassic and Early Cretaceous of Eur...

Background Jainemys pisdurensis comb. nov. is an extinct pleurodiran turtle from the Late Cretaceous (Maastrichtian) of India, previously referred to Carteremys and Shweboemys . The holotype, an eroded skull, had been collected near the village of Pisdura, south of Nagpur, in Maharashtra State, while all referred shell material originates from coev...

The newly discovered plattenkalk (platy limestone) locality of Wattendorf, southern Germany, has yielded a diverse fauna and flora dated to the base of the late Kimmeridgian, Late Jurassic. We here describe three fossil turtle specimens that were recovered during systematic excavations of a distinct, 15 cm thick package of plattenkalks by the Natur...

Neogene (Siwalik-aged) deposits from India and Pakistan have yielded many vertebrate fossils, of which most were named during the 19th century, including numerous geoemydid turtles. In contrast to many other faunal components from the Siwaliks, geoemydids have not undergone taxonomic revision for more than a century and most fossils have therefore...

Peltochelys duchastelii is an enigmatic turtle from Early Cretaceous (middle Barremian–early Aptian) Sainte-Barbe Formation of Bernissart, Belgium. In more recent literature, there has been strong support for the trionychian affinities of this taxon, but this interpretation is less consistent with external data, in particular biogeography and tempo...

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. La...

Baenidae is a clade of paracryptodiran turtles known from the late Early Cretaceous to Eocene of North America. The proposed sister-group relationship of Baenidae to Pleurosternidae, a group of turtles known from sediments dated as early as the Late Jurassic, suggests a ghost lineage that crosses the early Early Cretaceous. We here document a new s...

Background Indochelys spatulata is an extinct turtle from the Early to Middle Jurassic Kota Formation of the Pranhita–Godavari Gondwana basin, India. The holotype and previously only known specimen is a partially eroded shell that had been collected near Kota village, north of Sironcha, in Maharashtra State. Phylogenetic analyses have consistently...

Cardichelyon rogerwoodi is an enigmatic fossil turtle from the late Paleocene to early Eocene of North America. Previous analyses suggested affiliation with Testudinoidea, in particular the big-headed turtle Platysternon megacephalum , based on the presence of multiple musk-duct foramina and a large head. We here highlight previously undocumented c...

The five extinct giant tortoises of the genus Cylindraspis belong to the most iconic species of the enigmatic fauna of the Mascarene Islands that went largely extinct after the discovery of the islands. To resolve the phylogeny and biogeography of Cylindraspis, we analysed a data set of 45 mitogenomes that includes all lineages of extant tortoises...

The uppermost Cretaceous (Maastrichtian) Hell Creek Formation in North America has yielded a diverse assemblage of fossil turtles dominated by baenids. A population of over 30 individual skeletons from the Hell Creek Formation of North Dakota comprises a new baenid turtle, Saxochelys gilberti, increasing the number of recognized Hell Creek turtles...

The fossil record of nonbaenid paracryptodires ranges from the Late Jurassic (Kimmeridgian) to the Paleocene of North America and Europe only. Earlier remains may be present as early as the Middle Jurassic (Bathonian). Only a single dispersal event is documented between the two continents after their breakup during the Cretaceous in the form of the...

A new fossil site in a previously unexplored part of western Madagascar (the Beanka Protected Area) has yielded remains of many recently extinct vertebrates, including giant lemurs (Babakotia radofilai, Palaeopropithecus kelyus, Pachylemur sp., and Archaeolemur edwardsi), carnivores (Cryptoprocta spelea), the aardvark-like Plesiorycteropus sp., and...

Biogeographic analyses including our complete data set suggest that the ancestor of Cylindraspis lived in Africa and island-hopped to the Mascarenes circumventing Madagascar. According to our data, the Mascarene giant tortoises were definitely not introduced by humans.

Background In the last 20 years, a general picture of the evolutionary relationships between geoemydid turtles (ca. 70 species distributed over the Northern hemisphere) has emerged from the analysis of molecular data. However, there is a paucity of good traditional morphological characters that correlate with the phylogeny, which are essential for...

The middle ear of turtles differs from other reptiles in being separated into two distinct compartments. Several ideas have been proposed as to why the middle ear is compartmentalized in turtles, most suggesting a relationship with underwater hearing. Extant turtle species span fully marine to strictly terrestrial habitats, and ecomorphological hyp...

The fossil record of non-baenid paracryptodires ranges from the Middle Jurassic (Bathonian) to the Paleocene of North America and Europe only. Only a single dispersal event is documented between the two continents following their breakup during the Cretaceous in the form of the appearance of the Compsemys lineage in the Paleocene of France. Non bae...

Background Testudinoidea is a major clade of turtles that has colonized different ecological environments across the globe throughout the Tertiary. Aquatic testudinoids have a particularly rich fossil record in the Tertiary of the northern hemisphere, but little is known about the evolutionary history of the group, as the phylogenetic relationships...

Here we document the morphology of the only known skull of a carettochelyid turtle from North America. The specimen originates from the middle Eocene (early Uintan) Washakie Formation of Sweetwater County, Wyoming, and is referred to Anosteira pulchra based on temporal considerations. The skull of Anosteira pulchra broadly corresponds in its morpho...

Background Piramys auffenbergi was described as an emydine turtle based on a well-preserved skull retrieved from late Miocene deposits exposed on Piram Island, India. The description and figures provided in the original publication are vague and do not support assignment to Emydinae. This taxon has mostly been ignored by subsequent authors. Materi...

Several attempts to resolve the phylogeny of turtles in the clade Geoemydidae using morphology have been unsuccessful, in part because of unusually high levels of polymorphism. This has hindered the integration of the geoemydid fossil record into a phylogenetic framework. Many methods, shown to improve phylogenetic inference, allow the incorporatio...

New shell material of a trionychid turtle from the Upper Cretaceous (upper Campanian) Fossil Forest Member of the Fruitland Formation of northwestern New Mexico represents a new species, Gilmoremys gettyspherensis . The material consists of right costals I–III, V, VI, and VIII, left costals V, VII, and VIII, the left half of the entoplastron, the r...

The internal carotid system has played an important role in the systematics of fossil turtles, including baenids. A new, almost perfectly preserved specimen of Eubaena cephalica provides an opportunity to explore for the first time the cranial circulation and innervation of this taxon using CT (computed tomography) scans. We here document that the...

Several attempts to resolve the phylogeny of turtles in the clade Geoemydidae using morphology have been unsuccessful , in part because of unusually high levels of polymorphism. This has hindered the integration of the geoemydid fossil record into a phylogenetic framework. Many methods, shown to improve phylogenetic inference, allow the incorporati...

A fragmentary skeleton from the Kaiparowits Formation (Upper Campanian) of southern Utah represents a new taxon of chelydroid turtle herein named Lutemys warreni. Lutemys warreni differs from other chelydroids in the presence of a smooth shell, lack of plastral or carapacial fontanelles, and development of a thin, gracile plastron. A maximum parsim...

Background Helopanoplia distincta is an extinct soft-shelled turtle (Pan-Trionychidae) for which the type specimen is a fragmentary costal and the inguinal notch portion of the left hypoplastron from the Late Cretaceous (Maastrichtian) Lance Formation of Wyoming, USA that bear a distinct surface sculpture pattern consisting of raised tubercles. Ove...

Complete strict consensus and majority consensus topologies retrieved from the unweighted and weighted analysis and list of common synapomorphies from the unweighted analysis

Character taxon matrix used in phylogenetic analysis, including full character list and character state definitions and backbone constraint tree

In a previous study, we estimated the cranial disparity of turtles (Testudinata) through time using geometric morphometric data from both terminal taxa and hypothetical ancestors to compensate for temporal gaps in the fossil record. While this method yielded reasonable results for the Mesozoic and the early Cenozoic, we found a large drop in crania...

The Late Jurassic (Oxfordian to Tithonian) fossil record of Europe and South America has yielded a particularly rich assemblage of aquatic pan-cryptodiran turtles that are herein tentatively hypothesized to form a monophyletic group named Thalassochelydia. Thalassochelydians were traditionally referred to three families, Eurysternidae, Plesiochelyi...

The Late Jurassic (Oxfordian to Tithonian) fossil record of Europe and South America has yielded a particularly rich assemblage of aquatic pan-cryptodiran turtles that are herein tentatively hypothesized to form a monophyletic group named Thalassochelydia. Thalassochelydians were traditionally referred to three families, Eurysternidae, Plesiochelyi...

Eurysternum wagleri is one of the first named, yet most poorly understood turtles from the Late Jurassic of Europe. Over the years, many specimens have been referred to and many species synonymized with E. wagleri, but little consensus is apparent, and the taxonomy is therefore highly confusing. Based on the rare, only known illustration of the los...

Platychelys oberndorferi is a stem pleurodire from the Late Jurassic of Europe. The majority of informative specimens originate from the Late Jurassic (late Kimmeridgian) Turtle Limestones exposed north of the city of Solothurn, Switzerland, but these findings remain poorly documented despite their global importance for understanding the evolution...

Turtles (Testudinata) are a diverse group of reptiles that conquered a broad set of habitats and feeding ecologies over the course of their well-documented evolutionary history. We here investigate the cranial shape of 171 representatives of the turtle lineage and the relationship of shape to different habitat and diet preferences using two-dimensi...

Turtles of the clade Pan-Trionychidae have a rich fossil record in the Old World, ranging from the Early Cretaceous (Hauterivian) to the Holocene. The clade most probably originated in Asia during the Early Cretaceous but spread from there to the Americas and Europe by the Late Cretaceous, to India and Australia by the Eocene, and to Afro-Arabia by...

Turtles (Testudinata) are the clade of amniotes characterized by a complete turtle shell. New insights into the phylogeny of the group have revealed that a diverse assemblage of fossil turtles populate the stem lineage that lead to the turtle crown (Testudines). To aid communication, the terms Mesochelydia and Perichelydia are herein defined for tw...

Turtles (Testudinata) are a diverse group of amniotes that have a rich fossil record that extends back to the Late Triassic, but little is known about global patterns of disparity through time.We here investigate the cranial disparity of 172 representatives of the turtle lineage and their ancestors grouped into 20 time bins ranging from the Late Tr...

Background Turtles (Testudinata) are a successful lineage of vertebrates with about 350 extant species that inhabit all major oceans and landmasses with tropical to temperate climates. The rich fossil record of turtles documents the adaptation of various sub-lineages to a broad range of habitat preferences, but a synthetic biogeographic model is st...

Plastomenidae is a speciose clade of soft-shelled turtles (Trionychidae) known from Campanian to Eocene deposits throughout western North America. We here describe two large skulls from the Upper Cretaceous (Maastrichtian) Hell Creek Formation of Carter County, Montana, that document the adult morphology of the plastomenid Gilmoremys lancensis. Whe...

Background Bothremydidae is a clade of extinct pleurodiran turtles known from the Cretaceous to Paleogene of Africa, Europe, India, Madagascar, and North and South America. The group is most diverse during the Late Cretaceous to Paleogene of Africa. Little is known, however, about the early evolution of the group. Methods We here figure and descri...

New cranial and postcranial material of the baenid turtle Neurankylus from the Paleocene Nacimiento Formation (Torrejonian NALMA) of northwestern New Mexico represents a new species, Neurankylus torrejonensis . The material consists of a fragmented but mostly complete skull, a partial carapace and plastron, portions of both humeri, a partial pelvis...

Turtles of the total clade Pan-Kinosternoidea have a relatively poor fossil record that extends back to the Late Cretaceous (Campanian). The clade is found only in North America during its early history, but dispersed to Central America no later than the Miocene and to South America no later than the Pleistocene. Ancestral pan-kinosternoids were li...

Turtles of the total clade Pan-Chelydridae have a relatively sparse fossil record that reaches back to the Late Cretaceous (Santonian). The clade was only present in North America during the Cretaceous but spread along unclear routes to Asia and Europe during the Paleocene, only to go extinct on those continents by the end of the Pliocene. Final di...