Juliana Sterli - Profile on Academia.edu (original) (raw)
Papers by Juliana Sterli
During early development of turtles and other amniotes, the parabasisphenoid, or basisphenoid s.l... more During early development of turtles and other amniotes, the parabasisphenoid, or basisphenoid s.l., is formed by at least two centers of ossification: the endochondral basisphenoid s.s. and the dermal parasphenoid. This fusion is usually so dramatic that the two elements cannot be distinguished from each other in the adult stage. Here we describe the basicranium of two individuals of Mesozoic turtles from Europe, Plesiochelys etalloni and Pleurosternon bullockii, partly using micro-CT scans, and show that in both taxa para-and basisphenoid remain distinguishable throughout life. We also identify the extent that each of the two elements has contributed to the formation of the braincase floor. Because the structure of the parabasisphenoid determines the course of the internal carotid artery into the skull, our findings allow us to discuss the early evolution of the carotid pattern and the turtle basicranium in new detail. By surveying the main patterns of carotid circulation in extinct and extant turtles, we bring new evidence to the idea that it was largely the ossification of the parasphenoid which, along with the closure of the interpterygoid vacuity and the posterior extension of the pterygoids, shaped the internal carotid patterns as seen in modern turtles.
Acta Palaeontologica Polonica, 2007
The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Forma... more The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Formation, Arizona, USA. The detailed description of this taxon's cranium offered in this paper demonstrates that this turtle presents a mixture of primitive and derived character states. Among others, the presence of an interpterygoid vacuity, a basipterygoid process, a prootic that is exposed in ventral view, and a foramen posterius canalis carotici interni that is formed entirely by the basisphenoid are generally considered primitive for turtles. On the other hand, the presence of an undivided apertura narium, a well developed cavum tympani, an incipient cavum postoticum, and an unpaired vomer are considered to be derived. Kayentachelys aprix has previously been hypothesized to be the oldest stem cryptodiran turtle because of the presence of a flat, vertical plate on the processus pterygoideus externus, and the presence of a processus trochlearis oticum. However, the presence of these characters cannot be confirmed in the available specimens. Other putative stemcryptodiran characters, such as the prefrontal-vomer contact and the presence of an epipterygoid, are herein corroborated as being symplesiomorphies, because they generally appear to be present in basal turtles.
Biology Letters, Mar 10, 2008
Turtles have been known since the Upper Triassic (210 Myr old); however, fossils recording the fi... more Turtles have been known since the Upper Triassic (210 Myr old); however, fossils recording the first steps of turtle evolution are scarce and often fragmentary. As a consequence, one of the main questions is whether living turtles (Testudines) originated during the Late Triassic (210 Myr old) or during the Middle to Late Jurassic (ca 160 Myr old). The discovery of the new fossil turtle, Condorchelys antiqua gen. et sp. nov., from the Middle to Upper Jurassic (ca 160-146 Myr old) of South America (Patagonia, Argentina), presented here sheds new light on early turtle evolution. An updated cladistic analysis of turtles shows that C. antiqua and other fossil turtles are not crown turtles, but stem turtles. This cladistic analysis also shows that stem turtles were more diverse than previously thought, and that until the Middle to Upper Jurassic there were turtles without the modern jaw closure mechanism.
Acta Zoologica, Dec 22, 2010
Modern cladistic analysis is characterized by the assembly of increasingly larger data sets coupl... more Modern cladistic analysis is characterized by the assembly of increasingly larger data sets coupled with the use of congruence as the final test of homology. Some critics of this development have recently called for a return to more detailed primary homology analysis while questioning the utility of congruence. This discussion appears to be central to the debate regarding the phylogenetic relationships of basal turtles, as the large data sets developed by us have been criticized recently for utilizing poorly constructed characters and including too many homoplasy-prone characters. Our analysis of this critique reveals that (1) new information regarding poorly understood taxa has a greater impact on the outcome of turtle phylogenies than the characters under dispute; (2) most current turtle phylogenies differ in taxon sampling, not character sampling, and so it appears illogical to condemn a particular analysis for its character sampling; (3) even evolutionary taxonomists should agree that key characters utilized to resolve basal turtle relationships cannot be thought to be 'infallible'; (4) whereas various criteria provide positive evidence for homology, only congruence provides positive evidence for non-homology; and (5) a stalemate between conflicting camps within a congruence frame work is preferable to the ad hoc dismissal of data sets, because authoritative statements are untestable.
Revista de la Asociación Geológica Argentina, Dec 1, 2008
The plant and tetrapod fossil record of the Cañadón Asfalto Formation (Middle to Late Jurassic) f... more The plant and tetrapod fossil record of the Cañadón Asfalto Formation (Middle to Late Jurassic) found in Cerro Cóndor area (Chubut Province) is summarized here. The flora is dominated by conifers (Araucariaceae, Cupressaceae sensu lato) but also includes ferns and equisetaleans. The tetrapod fauna is composed of dinosaur taxa described in the 70's as well as other remains recently described and other vertebrate groups such as amphibians, turtles, and mammals. The amphibian remains have been interpreted as representatives of a new species of Notobatrachus, considered one of the most basal members of the anuran lineage. Similarly, turtle remains have been recently recognized as a new species of basal turtle, bringing valuable information about the early evolution of this group. The dinosaur remains are largely dominated by saurischian taxa, represented by basal forms of Eusauropoda and Tetanurae. In addition, three different mammalian species have been identified and considered as early representatives of an endemic Gondwanan mammalian fauna. The fossil record of this formation represents the most completely known biota from the continental Middle to Late Jurassic of the Southern Hemisphere and one of the most complete of the entire world.
Contributions to zoology, Sep 24, 2010
The origin and evolution of the crown-group of turtles (Cryptodira + Pleurodira) is one of the mo... more 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.
Acta Palaeontologica Polonica, 2019
Fossil turtles are one of the least studied clades in regard to endocranial anatomy. Recently, th... more Fossil turtles are one of the least studied clades in regard to endocranial anatomy. Recently, the use of non-invasive technologies, such as radiographic computed tomography (CT), increased the knowledge of the neuroanatomy of several extinct and extant taxa. Here, we provide the description of the nasal cavity, cranial endocast, and inner ear of the stem turtle Naomichelys speciosa based on digital 3D reconstructions. This terrestrial form is characterized by a nasal cavity with anteroposteriorly elongated vestibulum and a large cavum nasi proprium, traits typically related to terrestrial habits. The large olfactory region of the cavum nasi proprium suggests that olfaction was probably the most important sense for this species. Our description of N. speciosa adds novel information to the knowledge of endocranial anatomy in early turtle evolution and provides an important foundation for future analyses and comparisons.
Publicación Electrónica de la Asociación Paleontológica Argentina
The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been repor... more The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been reported from the Mata Amarilla Formation (Cenomanian), the Cerro Fortaleza Formation (Campanian-Maastrichtian), and the Chorrillo Formation (early Maastrichtian). In this contribution, we examined all the turtle remains recovered from six localities in the Mata Amarilla Formation, nearby Mata Amarilla farm (Santa Cruz Province, Argentina). These fossils are housed at the "Padre Molina" Museum in Río Gallegos, Santa Cruz. Most of the carapace and plastral remains are conferred to an indeterminate small species of cf. Prochelidella sp., while the remaining fragments are attributed to a mid-sized species of an indeterminate Chelidae. Prochelidella spp. is a group of turtles distributed in Chubut, Río Negro, Neuquén, and Mendoza provinces, ranging from the Aptian to the Maastrichtian, with two main gaps (late Albian and Coniacian-Santonian). The recognition of cf. Prochelidella sp. in the Austral-Magallanes Basin extends the geographic range of this group more than 500 km south to the previously known southernmost record of Prochelidella, Pr. argentinae, from the Golfo San Jorge Basin (Chubut, Argentina).
Paleoherpetología en El Museo Paleontológico Egidio Feruglio (Trelew, Chubut)
Publicación Electrónica de la Asociación Paleontológica Argentina
Swiss Journal of Palaeontology, 2021
Over the last 25 years, researchers, mostly paleontologists, have developed a system of rank-free... more 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 majority of previously defined clade names for extinct and extant turtles into this new nomenclatural framework. Some previously defined names are converted with minor adjustments. We also define a number of new clade names to close apparent nomenclatural gaps. In total, we establish 113 clade names, of which 79 had already received phylogenetic definitions and 34 are new.
Background. Condorchelys antiqua is a stem turtle previously described from the Queso Rallado Loc... more Background. Condorchelys antiqua is a stem turtle previously described from the Queso Rallado Locality, Cañadón Asfalto Formation (Early-Middle Jurassic), Chubut, Argentina. In 2014 a skull (MPEF-PV 10900) and an articulated shell with associated postcranial remains (MPEF-PV 10884) of C. antiqua were discovered in the mentioned locality. Methods. The new specimens have been prepared by L. Reiner (technician at the Museo Egidio Feruglio) and then studied using the regular paleontological methodology (e.g., direct observations and under the microscope, photography, and drawings). The new data provided by these two specimens, plus some other isolated remains that were re-prepared, allowed us to score a 25% more of the characters of C. antiqua in the most complete up to date matrix for Mesozoic turtles. The matrix was build in Mesquite and analyzed under maximum parsimony in TNT. We performed two rounds of Tree Bisection Reconnection and calculated a strict consensus. Branch supports we...
Contributions to Zoology, 2020
Pan-Chelidae (Testudines, Pleurodira) is a group of side-necked turtles with a currently disjoint... more Pan-Chelidae (Testudines, Pleurodira) is a group of side-necked turtles with a currently disjointed distribution in South America and Australasia and characterized by two morphotypes: the long-necked and the short-necked chelids. Both geographic groups include both morphotypes, but different phylogenetic signals are obtained from morphological and molecular data, suggesting the monophyly of the long-necked chelids or the independent evolution of this trait in both groups. In this paper, we addressed this conflict by compiling and editing available molecular and morphological data for Pan-Chelidae, and performing phylogenetic and dating analyses over the individual and the combined datasets. Our total-evidence phylogenetic analysis recovered the clade Chelidae as monophyletic and as sister group of a clade of South American extinct chelids; furthermore Chelidae retained inside the classical molecular structure with the addition of extinct taxa in both the Australasian and the South A...
Gondwana Research, 2019
The Cretaceous Cerro Barcino Formation (Chubut Group) of Central Patagonia, Argentina has yielded... more The Cretaceous Cerro Barcino Formation (Chubut Group) of Central Patagonia, Argentina has yielded a remarkable fossil vertebrate fauna, which form important components of the South American "mid-Cretaceous" fauna, including titanosauriform sauropod dinosaurs, theropod dinosaurs, crocodyliforms, turtles, and lepidosauromorphs. However, a lack of robust chronostratigraphic framework for its fossil occurrences has so far hampered a full realization of their paleobiologic significance. This contribution presents new stratigraphic, sedimentologic, and U-Pb isotopic age data from 11 localities throughout the Patagonian Somuncurá-Canadón Asfalto Basin and analyzes the evolutionary characteristics of the Cerro Barcino fauna within the biostratigraphic context of the Cretaceous of Gondwana. Four new high-precision 206 Pb/ 238 U zircon dates by the CA-ID-TIMS method range from 118.497 ± 0.063 Ma to 98.466 ± 0.048 Ma (2σ internal errors) and limits the Puesto La Paloma, Cerro Castaño and Las Plumas members of the Cerro Barcino Formation largely to the Aptian, Albian and Cenomanian stages of the Cretaceous, respectively. Accordingly, the majority of the Cerro Barcino vertebrates fall within a ~118-110 Ma time interval in the latest Early Cretaceous, which makes them the oldest documented component of the "mid-Cretaceous" faunal assemblage of Gondwana. Paleobiologic analyses of the latter assemblage suggests a ~10 m.y. period of faunistic stability characterized by only minor evolutionary novelties or faunal turnovers.
Los objetivos de la presente Tesis fueron estudiar la anatomía de las tortugas del Jurásico conti... more Los objetivos de la presente Tesis fueron estudiar la anatomía de las tortugas del Jurásico continental de Patagonia, establecer sus relaciones filogenéticas dentro del grupo y comparar los resultados con la paleogeografía de la época. Se conocen, hasta el momento, tres localidades en Patagonia con restos de tortugas continentales del Jurásico, todas ellas ubicadas en la provincia de Chubut en las cercanías de la villa de Cerro Cóndor. Dos localidades están ubicadas en afloramientos de la Formación Cañadón Asfalto (Queso Rallado y El Bagual), mientras que la tercera lo está en afloramientos de la Formación Cañadón Calcáreo (Estancia Dionide Mesa). Los restos más completos y diagnósticos se recuperaron de la localidad Queso Rallado y los mismos fueron identificados como una nueva especie, Condorchelys antiqua Sterli 2008, la cual presenta una combinación de caracteres plesiomórficos y apomórficos. Los restos hallados en las otras localidades son fragmentarios, lo cual no permite una ...
Royal Society open science, 2018
Pleurodires or side-necked turtles are today restricted to freshwater environments of South Ameri... more Pleurodires or side-necked turtles are today restricted to freshwater environments of South America, Africa-Madagascar and Australia, but in the past they were distributed much more broadly, being found also on Eurasia, India and North America, and marine environments. Two hypotheses were proposed to explain this distribution; in the first, vicariance would have shaped the current geographical distribution and, in the second, extinctions constrained a previously widespread distribution. Here, we aim to reconstruct pleurodiran biogeographic history and diversification patterns based on a new phylogenetic hypothesis recovered from the analysis of the largest morphological dataset yet compiled for the lineage, testing which biogeographical process prevailed during its evolutionary history. The resulting topology generally agrees with previous hypotheses of the group and shows that most diversification shifts were related to the exploration of new niches, e.g. littoral or marine radiati...
Acta Palaeontologica Polonica, 2017
Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous... more Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2-11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni.
Comparative neuroanatomy of extinct horned turtles (Meiolaniidae) and extant terrestrial turtles (Testudinidae), with comments on the palaeobiological implications of selected endocranial features
Zoological Journal of the Linnean Society, 2017
Turtles are one of the least explored clades of reptiles with respect to palaeoneuroanatomy. Few ... more Turtles are one of the least explored clades of reptiles with respect to palaeoneuroanatomy. Few detailed descriptions of endocranial features such as the brain morphology or inner ear exist for ex ...
Papers in Palaeontology, 2016
Until recently, the record of Mesozoic turtles in Mexico has been restricted to the Cretaceous. N... more Until recently, the record of Mesozoic turtles in Mexico has been restricted to the Cretaceous. New discoveries in the Sabinal Formation (Tlaxiaco, Oaxaca) have extended the record into the Kimmeridgian (Late Jurassic). The Sabinal Formation is part of the Tlaxiaco Basin, which was a depocenter of continental and marine sediments dominated by transgressive-regressive marine conditions during the Jurassic-Cretaceous. The new turtle described here consists of an almost complete carapace associated with a plastron. Based on the unique combination of characters, this turtle is identified as a new species of Platychelyidae here named Notoemys tlaxiacoensis. Platychelyid characters in this specimen include the presence of the sulcus between vertebral 3 and 4 located on neural 6, the presence of a central plastral fontanelle, and a pair of reduced mesoplastra. The occurrence of Kimmeridgian platychelyids in Mexico confirms that the Hispanic Corridor acted as a connection between Tethyan and Palaeopacific faunas.
Cretaceous Research, 2017
A new genus and species of panchelid turtle (Mendozachelys wichmanni gen. et sp. nov.) from the u... more A new genus and species of panchelid turtle (Mendozachelys wichmanni gen. et sp. nov.) from the upper Campanianelower Maastrichtian Loncoche Formation (southern Mendoza Province, Argentina) is described here. This species is represented by only one complete and articulated large specimen (carapace length estimated in 950 mm) that was recovered from tidal flat deposits. A detailed morphological and osteohistological description is made, recognizing autapomorphic characters that allow differentiating this taxon from the rest of extant and extinct panchelids. Osteohistological characters suggest an aquatic to semi-aquatic life style for Mendozachelys wichmanni gen. et sp. nov. Phylogenetic analysis based on morphological data suggested that this new taxon is nested within crown Chelidae. Both phylogenetic signals (morphological and molecular) about the assessment of long-necked chelids monophyly or polyphyly are discussed.
During early development of turtles and other amniotes, the parabasisphenoid, or basisphenoid s.l... more During early development of turtles and other amniotes, the parabasisphenoid, or basisphenoid s.l., is formed by at least two centers of ossification: the endochondral basisphenoid s.s. and the dermal parasphenoid. This fusion is usually so dramatic that the two elements cannot be distinguished from each other in the adult stage. Here we describe the basicranium of two individuals of Mesozoic turtles from Europe, Plesiochelys etalloni and Pleurosternon bullockii, partly using micro-CT scans, and show that in both taxa para-and basisphenoid remain distinguishable throughout life. We also identify the extent that each of the two elements has contributed to the formation of the braincase floor. Because the structure of the parabasisphenoid determines the course of the internal carotid artery into the skull, our findings allow us to discuss the early evolution of the carotid pattern and the turtle basicranium in new detail. By surveying the main patterns of carotid circulation in extinct and extant turtles, we bring new evidence to the idea that it was largely the ossification of the parasphenoid which, along with the closure of the interpterygoid vacuity and the posterior extension of the pterygoids, shaped the internal carotid patterns as seen in modern turtles.
Acta Palaeontologica Polonica, 2007
The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Forma... more The fossil turtle Kayentachelys aprix is known from Early Jurassic sediments of the Kayenta Formation, Arizona, USA. The detailed description of this taxon's cranium offered in this paper demonstrates that this turtle presents a mixture of primitive and derived character states. Among others, the presence of an interpterygoid vacuity, a basipterygoid process, a prootic that is exposed in ventral view, and a foramen posterius canalis carotici interni that is formed entirely by the basisphenoid are generally considered primitive for turtles. On the other hand, the presence of an undivided apertura narium, a well developed cavum tympani, an incipient cavum postoticum, and an unpaired vomer are considered to be derived. Kayentachelys aprix has previously been hypothesized to be the oldest stem cryptodiran turtle because of the presence of a flat, vertical plate on the processus pterygoideus externus, and the presence of a processus trochlearis oticum. However, the presence of these characters cannot be confirmed in the available specimens. Other putative stemcryptodiran characters, such as the prefrontal-vomer contact and the presence of an epipterygoid, are herein corroborated as being symplesiomorphies, because they generally appear to be present in basal turtles.
Biology Letters, Mar 10, 2008
Turtles have been known since the Upper Triassic (210 Myr old); however, fossils recording the fi... more Turtles have been known since the Upper Triassic (210 Myr old); however, fossils recording the first steps of turtle evolution are scarce and often fragmentary. As a consequence, one of the main questions is whether living turtles (Testudines) originated during the Late Triassic (210 Myr old) or during the Middle to Late Jurassic (ca 160 Myr old). The discovery of the new fossil turtle, Condorchelys antiqua gen. et sp. nov., from the Middle to Upper Jurassic (ca 160-146 Myr old) of South America (Patagonia, Argentina), presented here sheds new light on early turtle evolution. An updated cladistic analysis of turtles shows that C. antiqua and other fossil turtles are not crown turtles, but stem turtles. This cladistic analysis also shows that stem turtles were more diverse than previously thought, and that until the Middle to Upper Jurassic there were turtles without the modern jaw closure mechanism.
Acta Zoologica, Dec 22, 2010
Modern cladistic analysis is characterized by the assembly of increasingly larger data sets coupl... more Modern cladistic analysis is characterized by the assembly of increasingly larger data sets coupled with the use of congruence as the final test of homology. Some critics of this development have recently called for a return to more detailed primary homology analysis while questioning the utility of congruence. This discussion appears to be central to the debate regarding the phylogenetic relationships of basal turtles, as the large data sets developed by us have been criticized recently for utilizing poorly constructed characters and including too many homoplasy-prone characters. Our analysis of this critique reveals that (1) new information regarding poorly understood taxa has a greater impact on the outcome of turtle phylogenies than the characters under dispute; (2) most current turtle phylogenies differ in taxon sampling, not character sampling, and so it appears illogical to condemn a particular analysis for its character sampling; (3) even evolutionary taxonomists should agree that key characters utilized to resolve basal turtle relationships cannot be thought to be 'infallible'; (4) whereas various criteria provide positive evidence for homology, only congruence provides positive evidence for non-homology; and (5) a stalemate between conflicting camps within a congruence frame work is preferable to the ad hoc dismissal of data sets, because authoritative statements are untestable.
Revista de la Asociación Geológica Argentina, Dec 1, 2008
The plant and tetrapod fossil record of the Cañadón Asfalto Formation (Middle to Late Jurassic) f... more The plant and tetrapod fossil record of the Cañadón Asfalto Formation (Middle to Late Jurassic) found in Cerro Cóndor area (Chubut Province) is summarized here. The flora is dominated by conifers (Araucariaceae, Cupressaceae sensu lato) but also includes ferns and equisetaleans. The tetrapod fauna is composed of dinosaur taxa described in the 70's as well as other remains recently described and other vertebrate groups such as amphibians, turtles, and mammals. The amphibian remains have been interpreted as representatives of a new species of Notobatrachus, considered one of the most basal members of the anuran lineage. Similarly, turtle remains have been recently recognized as a new species of basal turtle, bringing valuable information about the early evolution of this group. The dinosaur remains are largely dominated by saurischian taxa, represented by basal forms of Eusauropoda and Tetanurae. In addition, three different mammalian species have been identified and considered as early representatives of an endemic Gondwanan mammalian fauna. The fossil record of this formation represents the most completely known biota from the continental Middle to Late Jurassic of the Southern Hemisphere and one of the most complete of the entire world.
Contributions to zoology, Sep 24, 2010
The origin and evolution of the crown-group of turtles (Cryptodira + Pleurodira) is one of the mo... more 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.
Acta Palaeontologica Polonica, 2019
Fossil turtles are one of the least studied clades in regard to endocranial anatomy. Recently, th... more Fossil turtles are one of the least studied clades in regard to endocranial anatomy. Recently, the use of non-invasive technologies, such as radiographic computed tomography (CT), increased the knowledge of the neuroanatomy of several extinct and extant taxa. Here, we provide the description of the nasal cavity, cranial endocast, and inner ear of the stem turtle Naomichelys speciosa based on digital 3D reconstructions. This terrestrial form is characterized by a nasal cavity with anteroposteriorly elongated vestibulum and a large cavum nasi proprium, traits typically related to terrestrial habits. The large olfactory region of the cavum nasi proprium suggests that olfaction was probably the most important sense for this species. Our description of N. speciosa adds novel information to the knowledge of endocranial anatomy in early turtle evolution and provides an important foundation for future analyses and comparisons.
Publicación Electrónica de la Asociación Paleontológica Argentina
The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been repor... more The fossil record of Cretaceous turtles in Santa Cruz Province is scarce. Turtles have been reported from the Mata Amarilla Formation (Cenomanian), the Cerro Fortaleza Formation (Campanian-Maastrichtian), and the Chorrillo Formation (early Maastrichtian). In this contribution, we examined all the turtle remains recovered from six localities in the Mata Amarilla Formation, nearby Mata Amarilla farm (Santa Cruz Province, Argentina). These fossils are housed at the "Padre Molina" Museum in Río Gallegos, Santa Cruz. Most of the carapace and plastral remains are conferred to an indeterminate small species of cf. Prochelidella sp., while the remaining fragments are attributed to a mid-sized species of an indeterminate Chelidae. Prochelidella spp. is a group of turtles distributed in Chubut, Río Negro, Neuquén, and Mendoza provinces, ranging from the Aptian to the Maastrichtian, with two main gaps (late Albian and Coniacian-Santonian). The recognition of cf. Prochelidella sp. in the Austral-Magallanes Basin extends the geographic range of this group more than 500 km south to the previously known southernmost record of Prochelidella, Pr. argentinae, from the Golfo San Jorge Basin (Chubut, Argentina).
Paleoherpetología en El Museo Paleontológico Egidio Feruglio (Trelew, Chubut)
Publicación Electrónica de la Asociación Paleontológica Argentina
Swiss Journal of Palaeontology, 2021
Over the last 25 years, researchers, mostly paleontologists, have developed a system of rank-free... more 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 majority of previously defined clade names for extinct and extant turtles into this new nomenclatural framework. Some previously defined names are converted with minor adjustments. We also define a number of new clade names to close apparent nomenclatural gaps. In total, we establish 113 clade names, of which 79 had already received phylogenetic definitions and 34 are new.
Background. Condorchelys antiqua is a stem turtle previously described from the Queso Rallado Loc... more Background. Condorchelys antiqua is a stem turtle previously described from the Queso Rallado Locality, Cañadón Asfalto Formation (Early-Middle Jurassic), Chubut, Argentina. In 2014 a skull (MPEF-PV 10900) and an articulated shell with associated postcranial remains (MPEF-PV 10884) of C. antiqua were discovered in the mentioned locality. Methods. The new specimens have been prepared by L. Reiner (technician at the Museo Egidio Feruglio) and then studied using the regular paleontological methodology (e.g., direct observations and under the microscope, photography, and drawings). The new data provided by these two specimens, plus some other isolated remains that were re-prepared, allowed us to score a 25% more of the characters of C. antiqua in the most complete up to date matrix for Mesozoic turtles. The matrix was build in Mesquite and analyzed under maximum parsimony in TNT. We performed two rounds of Tree Bisection Reconnection and calculated a strict consensus. Branch supports we...
Contributions to Zoology, 2020
Pan-Chelidae (Testudines, Pleurodira) is a group of side-necked turtles with a currently disjoint... more Pan-Chelidae (Testudines, Pleurodira) is a group of side-necked turtles with a currently disjointed distribution in South America and Australasia and characterized by two morphotypes: the long-necked and the short-necked chelids. Both geographic groups include both morphotypes, but different phylogenetic signals are obtained from morphological and molecular data, suggesting the monophyly of the long-necked chelids or the independent evolution of this trait in both groups. In this paper, we addressed this conflict by compiling and editing available molecular and morphological data for Pan-Chelidae, and performing phylogenetic and dating analyses over the individual and the combined datasets. Our total-evidence phylogenetic analysis recovered the clade Chelidae as monophyletic and as sister group of a clade of South American extinct chelids; furthermore Chelidae retained inside the classical molecular structure with the addition of extinct taxa in both the Australasian and the South A...
Gondwana Research, 2019
The Cretaceous Cerro Barcino Formation (Chubut Group) of Central Patagonia, Argentina has yielded... more The Cretaceous Cerro Barcino Formation (Chubut Group) of Central Patagonia, Argentina has yielded a remarkable fossil vertebrate fauna, which form important components of the South American "mid-Cretaceous" fauna, including titanosauriform sauropod dinosaurs, theropod dinosaurs, crocodyliforms, turtles, and lepidosauromorphs. However, a lack of robust chronostratigraphic framework for its fossil occurrences has so far hampered a full realization of their paleobiologic significance. This contribution presents new stratigraphic, sedimentologic, and U-Pb isotopic age data from 11 localities throughout the Patagonian Somuncurá-Canadón Asfalto Basin and analyzes the evolutionary characteristics of the Cerro Barcino fauna within the biostratigraphic context of the Cretaceous of Gondwana. Four new high-precision 206 Pb/ 238 U zircon dates by the CA-ID-TIMS method range from 118.497 ± 0.063 Ma to 98.466 ± 0.048 Ma (2σ internal errors) and limits the Puesto La Paloma, Cerro Castaño and Las Plumas members of the Cerro Barcino Formation largely to the Aptian, Albian and Cenomanian stages of the Cretaceous, respectively. Accordingly, the majority of the Cerro Barcino vertebrates fall within a ~118-110 Ma time interval in the latest Early Cretaceous, which makes them the oldest documented component of the "mid-Cretaceous" faunal assemblage of Gondwana. Paleobiologic analyses of the latter assemblage suggests a ~10 m.y. period of faunistic stability characterized by only minor evolutionary novelties or faunal turnovers.
Los objetivos de la presente Tesis fueron estudiar la anatomía de las tortugas del Jurásico conti... more Los objetivos de la presente Tesis fueron estudiar la anatomía de las tortugas del Jurásico continental de Patagonia, establecer sus relaciones filogenéticas dentro del grupo y comparar los resultados con la paleogeografía de la época. Se conocen, hasta el momento, tres localidades en Patagonia con restos de tortugas continentales del Jurásico, todas ellas ubicadas en la provincia de Chubut en las cercanías de la villa de Cerro Cóndor. Dos localidades están ubicadas en afloramientos de la Formación Cañadón Asfalto (Queso Rallado y El Bagual), mientras que la tercera lo está en afloramientos de la Formación Cañadón Calcáreo (Estancia Dionide Mesa). Los restos más completos y diagnósticos se recuperaron de la localidad Queso Rallado y los mismos fueron identificados como una nueva especie, Condorchelys antiqua Sterli 2008, la cual presenta una combinación de caracteres plesiomórficos y apomórficos. Los restos hallados en las otras localidades son fragmentarios, lo cual no permite una ...
Royal Society open science, 2018
Pleurodires or side-necked turtles are today restricted to freshwater environments of South Ameri... more Pleurodires or side-necked turtles are today restricted to freshwater environments of South America, Africa-Madagascar and Australia, but in the past they were distributed much more broadly, being found also on Eurasia, India and North America, and marine environments. Two hypotheses were proposed to explain this distribution; in the first, vicariance would have shaped the current geographical distribution and, in the second, extinctions constrained a previously widespread distribution. Here, we aim to reconstruct pleurodiran biogeographic history and diversification patterns based on a new phylogenetic hypothesis recovered from the analysis of the largest morphological dataset yet compiled for the lineage, testing which biogeographical process prevailed during its evolutionary history. The resulting topology generally agrees with previous hypotheses of the group and shows that most diversification shifts were related to the exploration of new niches, e.g. littoral or marine radiati...
Acta Palaeontologica Polonica, 2017
Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous... more Rionegrochelys caldieroi de la Fuente, Maniel, and Jannello gen. et sp. nov. is a Late Cretaceous turtle from Rio Negro Province, Argentina. The holotype and the referred specimens of this new species show an unusual shell morphology and microanatomy. The proportion between the carapace and plastron and the peculiar morphology of the shell such as the heart shaped carapace, a very deep nuchal notch, peripheral bones 2-11 with strongly gutter, the first vertebral scute twice as wide as long and subrectangular in shape, the posterior margin of vertebral scute 5 is three lobe shaped, and the unexpected osteohistology characterized by a massive structure, with higher compactness (80.6%) than other chelids, suggests beyond doubt that this turtle may be considered a new taxon. A semi-aquatic habitat with tendency towards terrestrial environments is inferred for Rionegrochelys caldieroi similar to that of the extant pelomedusid Pelomedusa subrufa among the extant pleurodires. Rionegrochelys caldieroi is recovered as a stem chelid. This new species seems to be closely related to Bonapartemys bajobarrealis and the clade formed by Lomalatachelys neuquina plus Mendozachelys wichmanni.
Comparative neuroanatomy of extinct horned turtles (Meiolaniidae) and extant terrestrial turtles (Testudinidae), with comments on the palaeobiological implications of selected endocranial features
Zoological Journal of the Linnean Society, 2017
Turtles are one of the least explored clades of reptiles with respect to palaeoneuroanatomy. Few ... more Turtles are one of the least explored clades of reptiles with respect to palaeoneuroanatomy. Few detailed descriptions of endocranial features such as the brain morphology or inner ear exist for ex ...
Papers in Palaeontology, 2016
Until recently, the record of Mesozoic turtles in Mexico has been restricted to the Cretaceous. N... more Until recently, the record of Mesozoic turtles in Mexico has been restricted to the Cretaceous. New discoveries in the Sabinal Formation (Tlaxiaco, Oaxaca) have extended the record into the Kimmeridgian (Late Jurassic). The Sabinal Formation is part of the Tlaxiaco Basin, which was a depocenter of continental and marine sediments dominated by transgressive-regressive marine conditions during the Jurassic-Cretaceous. The new turtle described here consists of an almost complete carapace associated with a plastron. Based on the unique combination of characters, this turtle is identified as a new species of Platychelyidae here named Notoemys tlaxiacoensis. Platychelyid characters in this specimen include the presence of the sulcus between vertebral 3 and 4 located on neural 6, the presence of a central plastral fontanelle, and a pair of reduced mesoplastra. The occurrence of Kimmeridgian platychelyids in Mexico confirms that the Hispanic Corridor acted as a connection between Tethyan and Palaeopacific faunas.
Cretaceous Research, 2017
A new genus and species of panchelid turtle (Mendozachelys wichmanni gen. et sp. nov.) from the u... more A new genus and species of panchelid turtle (Mendozachelys wichmanni gen. et sp. nov.) from the upper Campanianelower Maastrichtian Loncoche Formation (southern Mendoza Province, Argentina) is described here. This species is represented by only one complete and articulated large specimen (carapace length estimated in 950 mm) that was recovered from tidal flat deposits. A detailed morphological and osteohistological description is made, recognizing autapomorphic characters that allow differentiating this taxon from the rest of extant and extinct panchelids. Osteohistological characters suggest an aquatic to semi-aquatic life style for Mendozachelys wichmanni gen. et sp. nov. Phylogenetic analysis based on morphological data suggested that this new taxon is nested within crown Chelidae. Both phylogenetic signals (morphological and molecular) about the assessment of long-necked chelids monophyly or polyphyly are discussed.