Teleosaurids were a clade of crocodylomorphs that attained near-global distribution during the Ju... more Teleosaurids were a clade of crocodylomorphs that attained near-global distribution during the Jurassic Period. Within Teleosauridae, one particular sub-clade of durophagous/macrophagous taxa achieved large body sizes and were apex predators in shallow marine environments during the Late Jurassic and Early Cretaceous in Europe and around the coast of the Tethys Seaway. Unfortunately, the origins of this clade are still poorly understood. 'Steneosaurus' obtusidens is a little-studied macrophagous species from the Oxford Clay Formation (Callovian, Middle Jurassic) of the UK and near Migné-les-Lourdines (Middle Callovian) in France. Despite being considered a sister taxon of the Late Jurassic taxon Machimosaurus, the taxonomy of 'S.' obtusidens remains unclear. Although three different synonymies have been proposed (variously a subjective synonym of other taxa), these taxonomic hypotheses have not been based on detailed anatomical comparisons and thus have not been tested. Here, we re-describe the holotype of 'S.' obtusidens, demonstrate that it is indeed a valid taxon, restrict the referred specimens to a fragmentary skeleton, nearly complete skull, and partial rostrum, and establish a new monotypic genus, Lemmysuchus. Our re-description reveals five autapomorphies for Lemmysuchus obtusidens and nine apomorphic characters that support the tribe Machimosaurini (Lemmysuchus + Machimosaurus).
A new pterosaur specimen comprising a partial skull and associated postcranial elements from the ... more A new pterosaur specimen comprising a partial skull and associated postcranial elements from the Lower Cretaceous Wessex Formation of Yaverland, Isle of Wight, southern England, is assigned to a new genus and species of ornithocheirid pterosaur, Caulkicephalus trimicrodon gen. et sp. nov., based on several unique features including a heterodont dentition in which the fifth, sixth and seventh teeth are reduced in size compared with those at positions 1e4 and 8e9; the presence of a frontoparietal crest and maxillopremaxillary crest that do not unite over the antorbital fenestra or cranium; a palatal ridge that extends no further forward than the eighth to ninth tooth pairs. The new taxon is the second species of pterosaur from the Wealden Group of the Wessex Basin.
For all of the nineteenth-century bone collectors working on Rodrigues, their main objective was ... more For all of the nineteenth-century bone collectors working on Rodrigues, their main objective was to search the caves for specimens of the Solitaire Pezophaps solitaria, the sister taxon of the Dodo Raphus cucullatus of neighbouring Mauritius. Rodrigues Island has an extensive calcarenite plain in the southwest of the island, which contains numerous caves. A number of expeditions explored the area and excavated the caves, especially during the 1860s and 1870s, resulting in the discovery of thousands of subfossil bones. Some details of these activities were published, and some of the expedition explorers left manuscript reports, all of which provide clues as to where they were excavating. Here, we present the results of a modern attempt to reconstruct the movements of these expeditions and to discover which of the numerous caves were visited and excavated.
Abstract Background: Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodi... more Abstract Background: Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey.
Background Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrop... more Background Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey.
Teleosaurids were a clade of marine crocodylomorphs that were globally distributed during the Jur... more Teleosaurids were a clade of marine crocodylomorphs that were globally distributed during the Jurassic Period. They evolved a wide range of body sizes, from small (~2–3 m) to very large (> 9 m). Until now, the largest known Middle Jurassic teleosaurid was ‘Steneosaurus’ obtusidens, from the Oxford Clay Formation of the UK. Here, we re-examine a very large Oxford Clay specimen (ilium, ischium, and femur) that had been tentatively attributed to ‘S.’ obtusidens. Based on comparative anatomical study with the ‘S.’ obtusidens holotype and referred specimens of Steneosaurus edwardsi and Steneosaurus leedsi, we conclude that this very large individual actually pertains to S. edwardsi. Based on comparisons with the Machimosaurus mosae neotype (which has a complete femur and skeleton), we estimate a total length in excess of 7 m for this large S. edwardsi individual, making it the largest known Middle Jurassic teleosaurid. Therefore, along with the closely related genus Machimosaurus, this clade of large-bodied Middle–Late Jurassic teleosaurids were the largest species during the first 100 million years of crocodylomorph evolution.
2016. Bigheaded marine crocodyliforms and why we must be cautious when using extant species as bo... more 2016. Bigheaded marine crocodyliforms and why we must be cautious when using extant species as body length proxies for long-extinct relatives. Palaeontologia Electronica 19.3.30A: 1-14 palaeo-electronica.org/content/2016/1554-teleosaurid-size-estimation ABSTRACT Body size is commonly used as a key variable for estimating ecomorphological trends at a macroevolutionary scale, making reliable body length estimates of fossil taxa critically important. Crocodylomorphs (extant crocodylians and their extinct relatives) evolved numerous 'aberrant' body-plans during their ~230 million-year history, ranging from 'hooved' terrestrial species to dolphin-like pelagic species. Such clades evolved distinct cranial and femoral scaling ratios (compared to total body length), thereby making extant taxa unsuitable proxies for estimating their body lengths. Here we illustrate that the fossil clade Teleosauridae also fits into this category. Teleosaurids were a predominately shallow marine clade that had a global distribution during the Jurassic. Known to have evolved a wide range of body lengths (2–5 m based on complete skeletons), there is currently no way of reliably estimating the size of incomplete specimens. This is surprising, as some teleosaurids have been considered very large (9–10 m in total length), thus making Teleosauridae the largest bodied clade during the first 100 million years of crocodylomorph evolution. Our examination and regression analyses of the best preserved teleosaurid skeletons demonstrates that: they were smaller than previously thought, with no known specimen exceeding 7.2 m in length; and that they had proportionally large skulls, and proportionally short femora, when compared to body length. Therefore, while many teleosaurid species evolved a cranial length of ≥1 m, these taxa would not necessarily have been larger than species living today. We advise caution when estimating body length for extinct taxa, especially for those outside of the crown group.
There is emerging consensus regarding late prehistoric island extinctions: humans are largely res... more There is emerging consensus regarding late prehistoric island extinctions: humans are largely responsible. Current research is providing a wealth of evidence for how humans might have so thoroughly transformed island environments soon after first colonization, and understanding this process has obvious relevance to current conservation and restoration strategies. Very few island groups worldwide were apparently colonized for the first time within the period of locally recorded history, however. Places that were first colonized historically offer a special opportunity to calibrate paleoecological methods and evaluate conclusions from other places. One pattern that has been observed from the fossil record of the peripheral continents and islands of all sizes and degrees of remoteness includes a stepwise process of 1) megafaunal decline; 2) increase in wildfire; 3) emergence of novel no-analog communities; and 4) broad-scale invasion by non-native cosmopolitan species. Although most of...
A new pterosaur specimen comprising a partial skull and associated postcranial elements from the ... more A new pterosaur specimen comprising a partial skull and associated postcranial elements from the Lower Cretaceous Wessex Formation of Yaverland, Isle of Wight, southern England, is assigned to a new genus and species of ornithocheirid pterosaur, Caulkicephalus trimicrodon gen. et sp. nov., based on several unique features including a heterodont dentition in which the fifth, sixth and seventh teeth are reduced in size compared with those at positions 1e4 and 8e9; the presence of a frontoparietal crest and maxillopremaxillary crest that do not unite over the antorbital fenestra or cranium; a palatal ridge that extends no further forward than the eighth to ninth tooth pairs. The new taxon is the second species of pterosaur from the Wealden Group of the Wessex Basin.
The dodo Raphus cucullatus Linnaeus, 1758, an extinct and flightless, giant pigeon endemic to Mau... more The dodo Raphus cucullatus Linnaeus, 1758, an extinct and flightless, giant pigeon endemic to Mauritius, has fascinated people since its discovery, yet has remained surprisingly poorly known. Until the mid-19th century, almost all that was known about the dodo was based on illustrations and written accounts by 17th century mariners, often of questionable accuracy. Furthermore, only a few fragmentary remains of dodos collected prior to the bird’s extinction exist. Our understanding of the dodo’s anatomy was substantially enhanced by the discovery in 1865 of subfossil bones in a marsh called the Mare aux Songes, situated in southeastern Mauritius. However, no contextual information was recorded during early excavation efforts, and the majority of excavated material comprised larger dodo bones, almost all of which were unassociated. Here we present a modern interdisciplinary analysis of the Mare aux Songes, a 4200-year-old multitaxic vertebrate concentration Lagerstatte. Our analysis of the deposits at this site provides the first detailed overview of the ecosystem inhabited by the dodo. The interplay of climatic and geological conditions led to the exceptional preservation of the animal and associated plant remains at the Mare aux Songes and provides a window into the past ecosystem of Mauritius. This interdisciplinary research approach provides an ecological framework for the dodo, complementing insights on its anatomy derived from the only associated dodo skeletons known, both of which were collected by Etienne Thirioux and are the primary subject of this memoir.
Teleosauridae was a group of largely marine Mesozoic crocodylomorphs, typically considered as aki... more Teleosauridae was a group of largely marine Mesozoic crocodylomorphs, typically considered as akin to “marine gavials” due to their elongate, tubular, polydont rostra that are indicative of a piscivorous diet. We here show that these extinct crocodylomorphs were more anatomically, and perhaps ecologically, varied than previously thought. We report the first evidence of denticles in a teleosaurid tooth, revealed by scanning electron microscopic (SEM) analysis of a tooth from the holotype of "Steneosaurus" obtusidens. These denticles are cryptic, because they are microscopic, not contiguous along the carinae (instead forming short series), and are detectable only using SEM. This incipient denticle morphology is similar to that recently discovered in a closely related group of marine crocodylomorphs, the Metriorhynchidae. In particular, the denticulation morphology of "Steneosaurus" is similar to that of the geosaurin metriorhynchid Torvoneustes, indicating that these two taxa may have employed similar feeding styles and that "S."obtusidens may have been a nearshore ecological analogue to the more offshore, fast-swimming geosaurins. Previous authors have considered "S." obtusidens and Machimosaurus to be durophagous, but the discovery of denticulated teeth indicates that they had a more varied diet and feeding style, and included flesh slicing as part of their feeding toolkit. It is currently unknown how extensive denticulate carinae may be in Teleosauridae, and we hypothesise that cryptic denticles may also be present in other marine crocodylomorphs once they are subjected to SEM study.
within this genus. We conclude that there were three European Machimosaurus species and another t... more within this genus. We conclude that there were three European Machimosaurus species and another taxon in Ethiopia. This conclusion is based on numerous lines of evidence: craniomandibular, dental and postcranial morphologies; differences in estimated total body length; geological age; geographical distribution; and hypothetical lifestyle. We re-diagnose the type species Machimosaurus hugii and limit referred specimens to only those from Upper Kimmeridgian-Lower Tithonian of Switzerland, Portugal and Spain. We also re-diagnose Machimosaurus mosae, demonstrate that it is an available name and restrict the species to the uppermost Kimmeridgian-lowermost Tithonian of northeastern France. We rediagnose and validate the species Machimosaurus nowackianus from Harrar, Ethiopia. Finally, we establish a new species, Machimosaurus buffetauti, for the Lower Kimmeridgian specimens of France and Germany (and possibly England and Poland). We hypothesize that Machimosaurus may have been analogous to the Pliocene-Holocene genus Crocodylus in having one large-bodied taxon suited to traversing marine barriers and additional, geographically limited taxa across its range.
The remote Indian Ocean island of Rodrigues, while largely of volcanic origin, also contains a la... more The remote Indian Ocean island of Rodrigues, while largely of volcanic origin, also contains a large body of eolian calcarenite with over thirty surveyed caves and many other karst features. Little is known, however, regarding the age andstratigraphy of the clastic deposits in the caves and the associated fossils of the highly endemic, now mostly extinct, fauna. On the Plaine Caverne and Plaine Corail of the southwestern part of the island, we obtained sediment cores up to 10 m in length and excavated bones of the extinct fauna from caves in the vicinity. Stratigraphic description and radiocarbon dating revealed that sediments in Canyon Tiyel, a collapsed-cave feature, primarily accumulated during the early and middle Holocene. Sedimentation in the canyon and adjacent caves has slowed in recent millennia, with the result that many bones of fauna that went extinct after human arrival in recent centuries are on or near the surface. The chemistry of the sediments and the alternate wet and dry regime of the cave and canyon surfaces are often not conducive to preservation of bone collagen and plant microfossils. Grotte Fougere, with an apparently unique anchialine pond inside a collapsing cave, however, contains over one meter of highly organic sediment with excellent preservation of plant and animal remains.
The alligatoroid Diplocynodon is by far the most common European eusuchian, being described or me... more The alligatoroid Diplocynodon is by far the most common European eusuchian, being described or mentioned from more than 200 localities and including several species, nine of which are considered valid and their phylogenetic relationships analyzed. Despite being among the first Diplocynodon species to be named, Diplocynodon hantoniensis from the Late Eocene of England was never described and figured with a modern approach. Most of the updated information on the morphology of D. hantoniensis derives indirectly from the character codings used for the cladistic analyses, which are available in the literature since the early 1990s. Subsequent studies were largely relying on a single data matrix produced more than a decade ago providing different topologies according to the number of taxa included in the analysis and their degree of completeness. Here we present the result of the revision of the whole Hordwell Cliff collection hosted at the Natural History Museum in London. The study of several nearly complete, well-preserved skulls and lower jaws, as well as dozens of other cranial and postcranial remains, allowed us to re-evaluate the codings of a few characters: in D. hantoniensis, the dentary symphysis extends from the posterior half of the fourth alveolus (BMNH 30397) to the center of the fifth alveolus (BMNH 30396, R1043); the surangular-articular suture is strongly bowed laterally within the glenoid fossa; the lateral edges of the palatines are parallel posteriorly; the ectopterygoid-pterygoid flexure does not disappear during ontogeny; and the quadratojugal-jugal suture lies at the posterior angle of the infratemporal fenestra. The result of these changes produced, however, a general polytomy of all the Diplocynodon species included in the analysis, indicating that further morphological data is needed to resolve the phylogenetic relationships of the species of this clade. MD supported by Synthesys (FR-TAF 967, BE-TAF 4907, GB-3097) and by the Spanish Ministerio de Economia y Competitividad (CGL2011-28681).
Teleosaurids were a clade of crocodylomorphs that attained near-global distribution during the Ju... more Teleosaurids were a clade of crocodylomorphs that attained near-global distribution during the Jurassic Period. Within Teleosauridae, one particular sub-clade of durophagous/macrophagous taxa achieved large body sizes and were apex predators in shallow marine environments during the Late Jurassic and Early Cretaceous in Europe and around the coast of the Tethys Seaway. Unfortunately, the origins of this clade are still poorly understood. 'Steneosaurus' obtusidens is a little-studied macrophagous species from the Oxford Clay Formation (Callovian, Middle Jurassic) of the UK and near Migné-les-Lourdines (Middle Callovian) in France. Despite being considered a sister taxon of the Late Jurassic taxon Machimosaurus, the taxonomy of 'S.' obtusidens remains unclear. Although three different synonymies have been proposed (variously a subjective synonym of other taxa), these taxonomic hypotheses have not been based on detailed anatomical comparisons and thus have not been tested. Here, we re-describe the holotype of 'S.' obtusidens, demonstrate that it is indeed a valid taxon, restrict the referred specimens to a fragmentary skeleton, nearly complete skull, and partial rostrum, and establish a new monotypic genus, Lemmysuchus. Our re-description reveals five autapomorphies for Lemmysuchus obtusidens and nine apomorphic characters that support the tribe Machimosaurini (Lemmysuchus + Machimosaurus).
A new pterosaur specimen comprising a partial skull and associated postcranial elements from the ... more A new pterosaur specimen comprising a partial skull and associated postcranial elements from the Lower Cretaceous Wessex Formation of Yaverland, Isle of Wight, southern England, is assigned to a new genus and species of ornithocheirid pterosaur, Caulkicephalus trimicrodon gen. et sp. nov., based on several unique features including a heterodont dentition in which the fifth, sixth and seventh teeth are reduced in size compared with those at positions 1e4 and 8e9; the presence of a frontoparietal crest and maxillopremaxillary crest that do not unite over the antorbital fenestra or cranium; a palatal ridge that extends no further forward than the eighth to ninth tooth pairs. The new taxon is the second species of pterosaur from the Wealden Group of the Wessex Basin.
For all of the nineteenth-century bone collectors working on Rodrigues, their main objective was ... more For all of the nineteenth-century bone collectors working on Rodrigues, their main objective was to search the caves for specimens of the Solitaire Pezophaps solitaria, the sister taxon of the Dodo Raphus cucullatus of neighbouring Mauritius. Rodrigues Island has an extensive calcarenite plain in the southwest of the island, which contains numerous caves. A number of expeditions explored the area and excavated the caves, especially during the 1860s and 1870s, resulting in the discovery of thousands of subfossil bones. Some details of these activities were published, and some of the expedition explorers left manuscript reports, all of which provide clues as to where they were excavating. Here, we present the results of a modern attempt to reconstruct the movements of these expeditions and to discover which of the numerous caves were visited and excavated.
Abstract Background: Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodi... more Abstract Background: Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey.
Background Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrop... more Background Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey.
Teleosaurids were a clade of marine crocodylomorphs that were globally distributed during the Jur... more Teleosaurids were a clade of marine crocodylomorphs that were globally distributed during the Jurassic Period. They evolved a wide range of body sizes, from small (~2–3 m) to very large (> 9 m). Until now, the largest known Middle Jurassic teleosaurid was ‘Steneosaurus’ obtusidens, from the Oxford Clay Formation of the UK. Here, we re-examine a very large Oxford Clay specimen (ilium, ischium, and femur) that had been tentatively attributed to ‘S.’ obtusidens. Based on comparative anatomical study with the ‘S.’ obtusidens holotype and referred specimens of Steneosaurus edwardsi and Steneosaurus leedsi, we conclude that this very large individual actually pertains to S. edwardsi. Based on comparisons with the Machimosaurus mosae neotype (which has a complete femur and skeleton), we estimate a total length in excess of 7 m for this large S. edwardsi individual, making it the largest known Middle Jurassic teleosaurid. Therefore, along with the closely related genus Machimosaurus, this clade of large-bodied Middle–Late Jurassic teleosaurids were the largest species during the first 100 million years of crocodylomorph evolution.
2016. Bigheaded marine crocodyliforms and why we must be cautious when using extant species as bo... more 2016. Bigheaded marine crocodyliforms and why we must be cautious when using extant species as body length proxies for long-extinct relatives. Palaeontologia Electronica 19.3.30A: 1-14 palaeo-electronica.org/content/2016/1554-teleosaurid-size-estimation ABSTRACT Body size is commonly used as a key variable for estimating ecomorphological trends at a macroevolutionary scale, making reliable body length estimates of fossil taxa critically important. Crocodylomorphs (extant crocodylians and their extinct relatives) evolved numerous 'aberrant' body-plans during their ~230 million-year history, ranging from 'hooved' terrestrial species to dolphin-like pelagic species. Such clades evolved distinct cranial and femoral scaling ratios (compared to total body length), thereby making extant taxa unsuitable proxies for estimating their body lengths. Here we illustrate that the fossil clade Teleosauridae also fits into this category. Teleosaurids were a predominately shallow marine clade that had a global distribution during the Jurassic. Known to have evolved a wide range of body lengths (2–5 m based on complete skeletons), there is currently no way of reliably estimating the size of incomplete specimens. This is surprising, as some teleosaurids have been considered very large (9–10 m in total length), thus making Teleosauridae the largest bodied clade during the first 100 million years of crocodylomorph evolution. Our examination and regression analyses of the best preserved teleosaurid skeletons demonstrates that: they were smaller than previously thought, with no known specimen exceeding 7.2 m in length; and that they had proportionally large skulls, and proportionally short femora, when compared to body length. Therefore, while many teleosaurid species evolved a cranial length of ≥1 m, these taxa would not necessarily have been larger than species living today. We advise caution when estimating body length for extinct taxa, especially for those outside of the crown group.
There is emerging consensus regarding late prehistoric island extinctions: humans are largely res... more There is emerging consensus regarding late prehistoric island extinctions: humans are largely responsible. Current research is providing a wealth of evidence for how humans might have so thoroughly transformed island environments soon after first colonization, and understanding this process has obvious relevance to current conservation and restoration strategies. Very few island groups worldwide were apparently colonized for the first time within the period of locally recorded history, however. Places that were first colonized historically offer a special opportunity to calibrate paleoecological methods and evaluate conclusions from other places. One pattern that has been observed from the fossil record of the peripheral continents and islands of all sizes and degrees of remoteness includes a stepwise process of 1) megafaunal decline; 2) increase in wildfire; 3) emergence of novel no-analog communities; and 4) broad-scale invasion by non-native cosmopolitan species. Although most of...
A new pterosaur specimen comprising a partial skull and associated postcranial elements from the ... more A new pterosaur specimen comprising a partial skull and associated postcranial elements from the Lower Cretaceous Wessex Formation of Yaverland, Isle of Wight, southern England, is assigned to a new genus and species of ornithocheirid pterosaur, Caulkicephalus trimicrodon gen. et sp. nov., based on several unique features including a heterodont dentition in which the fifth, sixth and seventh teeth are reduced in size compared with those at positions 1e4 and 8e9; the presence of a frontoparietal crest and maxillopremaxillary crest that do not unite over the antorbital fenestra or cranium; a palatal ridge that extends no further forward than the eighth to ninth tooth pairs. The new taxon is the second species of pterosaur from the Wealden Group of the Wessex Basin.
The dodo Raphus cucullatus Linnaeus, 1758, an extinct and flightless, giant pigeon endemic to Mau... more The dodo Raphus cucullatus Linnaeus, 1758, an extinct and flightless, giant pigeon endemic to Mauritius, has fascinated people since its discovery, yet has remained surprisingly poorly known. Until the mid-19th century, almost all that was known about the dodo was based on illustrations and written accounts by 17th century mariners, often of questionable accuracy. Furthermore, only a few fragmentary remains of dodos collected prior to the bird’s extinction exist. Our understanding of the dodo’s anatomy was substantially enhanced by the discovery in 1865 of subfossil bones in a marsh called the Mare aux Songes, situated in southeastern Mauritius. However, no contextual information was recorded during early excavation efforts, and the majority of excavated material comprised larger dodo bones, almost all of which were unassociated. Here we present a modern interdisciplinary analysis of the Mare aux Songes, a 4200-year-old multitaxic vertebrate concentration Lagerstatte. Our analysis of the deposits at this site provides the first detailed overview of the ecosystem inhabited by the dodo. The interplay of climatic and geological conditions led to the exceptional preservation of the animal and associated plant remains at the Mare aux Songes and provides a window into the past ecosystem of Mauritius. This interdisciplinary research approach provides an ecological framework for the dodo, complementing insights on its anatomy derived from the only associated dodo skeletons known, both of which were collected by Etienne Thirioux and are the primary subject of this memoir.
Teleosauridae was a group of largely marine Mesozoic crocodylomorphs, typically considered as aki... more Teleosauridae was a group of largely marine Mesozoic crocodylomorphs, typically considered as akin to “marine gavials” due to their elongate, tubular, polydont rostra that are indicative of a piscivorous diet. We here show that these extinct crocodylomorphs were more anatomically, and perhaps ecologically, varied than previously thought. We report the first evidence of denticles in a teleosaurid tooth, revealed by scanning electron microscopic (SEM) analysis of a tooth from the holotype of "Steneosaurus" obtusidens. These denticles are cryptic, because they are microscopic, not contiguous along the carinae (instead forming short series), and are detectable only using SEM. This incipient denticle morphology is similar to that recently discovered in a closely related group of marine crocodylomorphs, the Metriorhynchidae. In particular, the denticulation morphology of "Steneosaurus" is similar to that of the geosaurin metriorhynchid Torvoneustes, indicating that these two taxa may have employed similar feeding styles and that "S."obtusidens may have been a nearshore ecological analogue to the more offshore, fast-swimming geosaurins. Previous authors have considered "S." obtusidens and Machimosaurus to be durophagous, but the discovery of denticulated teeth indicates that they had a more varied diet and feeding style, and included flesh slicing as part of their feeding toolkit. It is currently unknown how extensive denticulate carinae may be in Teleosauridae, and we hypothesise that cryptic denticles may also be present in other marine crocodylomorphs once they are subjected to SEM study.
within this genus. We conclude that there were three European Machimosaurus species and another t... more within this genus. We conclude that there were three European Machimosaurus species and another taxon in Ethiopia. This conclusion is based on numerous lines of evidence: craniomandibular, dental and postcranial morphologies; differences in estimated total body length; geological age; geographical distribution; and hypothetical lifestyle. We re-diagnose the type species Machimosaurus hugii and limit referred specimens to only those from Upper Kimmeridgian-Lower Tithonian of Switzerland, Portugal and Spain. We also re-diagnose Machimosaurus mosae, demonstrate that it is an available name and restrict the species to the uppermost Kimmeridgian-lowermost Tithonian of northeastern France. We rediagnose and validate the species Machimosaurus nowackianus from Harrar, Ethiopia. Finally, we establish a new species, Machimosaurus buffetauti, for the Lower Kimmeridgian specimens of France and Germany (and possibly England and Poland). We hypothesize that Machimosaurus may have been analogous to the Pliocene-Holocene genus Crocodylus in having one large-bodied taxon suited to traversing marine barriers and additional, geographically limited taxa across its range.
The remote Indian Ocean island of Rodrigues, while largely of volcanic origin, also contains a la... more The remote Indian Ocean island of Rodrigues, while largely of volcanic origin, also contains a large body of eolian calcarenite with over thirty surveyed caves and many other karst features. Little is known, however, regarding the age andstratigraphy of the clastic deposits in the caves and the associated fossils of the highly endemic, now mostly extinct, fauna. On the Plaine Caverne and Plaine Corail of the southwestern part of the island, we obtained sediment cores up to 10 m in length and excavated bones of the extinct fauna from caves in the vicinity. Stratigraphic description and radiocarbon dating revealed that sediments in Canyon Tiyel, a collapsed-cave feature, primarily accumulated during the early and middle Holocene. Sedimentation in the canyon and adjacent caves has slowed in recent millennia, with the result that many bones of fauna that went extinct after human arrival in recent centuries are on or near the surface. The chemistry of the sediments and the alternate wet and dry regime of the cave and canyon surfaces are often not conducive to preservation of bone collagen and plant microfossils. Grotte Fougere, with an apparently unique anchialine pond inside a collapsing cave, however, contains over one meter of highly organic sediment with excellent preservation of plant and animal remains.
The alligatoroid Diplocynodon is by far the most common European eusuchian, being described or me... more The alligatoroid Diplocynodon is by far the most common European eusuchian, being described or mentioned from more than 200 localities and including several species, nine of which are considered valid and their phylogenetic relationships analyzed. Despite being among the first Diplocynodon species to be named, Diplocynodon hantoniensis from the Late Eocene of England was never described and figured with a modern approach. Most of the updated information on the morphology of D. hantoniensis derives indirectly from the character codings used for the cladistic analyses, which are available in the literature since the early 1990s. Subsequent studies were largely relying on a single data matrix produced more than a decade ago providing different topologies according to the number of taxa included in the analysis and their degree of completeness. Here we present the result of the revision of the whole Hordwell Cliff collection hosted at the Natural History Museum in London. The study of several nearly complete, well-preserved skulls and lower jaws, as well as dozens of other cranial and postcranial remains, allowed us to re-evaluate the codings of a few characters: in D. hantoniensis, the dentary symphysis extends from the posterior half of the fourth alveolus (BMNH 30397) to the center of the fifth alveolus (BMNH 30396, R1043); the surangular-articular suture is strongly bowed laterally within the glenoid fossa; the lateral edges of the palatines are parallel posteriorly; the ectopterygoid-pterygoid flexure does not disappear during ontogeny; and the quadratojugal-jugal suture lies at the posterior angle of the infratemporal fenestra. The result of these changes produced, however, a general polytomy of all the Diplocynodon species included in the analysis, indicating that further morphological data is needed to resolve the phylogenetic relationships of the species of this clade. MD supported by Synthesys (FR-TAF 967, BE-TAF 4907, GB-3097) and by the Spanish Ministerio de Economia y Competitividad (CGL2011-28681).
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Papers by Lorna Steel
specimens of the Solitaire Pezophaps solitaria, the sister taxon of the Dodo Raphus cucullatus of neighbouring Mauritius.
Rodrigues Island has an extensive calcarenite plain in the southwest of the island, which contains numerous caves. A number
of expeditions explored the area and excavated the caves, especially during the 1860s and 1870s, resulting in the discovery of
thousands of subfossil bones. Some details of these activities were published, and some of the expedition explorers left
manuscript reports, all of which provide clues as to where they were excavating. Here, we present the results of a modern
attempt to reconstruct the movements of these expeditions and to discover which of the numerous caves were visited and
excavated.
excavated bones of the extinct fauna from caves in the vicinity. Stratigraphic description and radiocarbon dating revealed that sediments in Canyon Tiyel, a collapsed-cave feature, primarily accumulated during the early and middle Holocene. Sedimentation in the canyon and adjacent caves has slowed in recent millennia, with the result that many
bones of fauna that went extinct after human arrival in recent centuries are on or near the surface. The chemistry of the sediments and the alternate wet and dry regime of the cave and canyon surfaces are often not conducive to preservation of bone collagen and plant microfossils. Grotte Fougere, with an apparently unique anchialine pond inside a collapsing cave, however, contains over one meter of highly organic sediment with excellent preservation of plant and animal remains.
a decade ago providing different topologies according to the number of taxa included in the analysis and their degree of completeness. Here we present the result of the revision of the whole Hordwell Cliff collection hosted at the Natural History Museum in London. The study of several nearly complete, well-preserved skulls and lower jaws, as well as dozens of other cranial and postcranial remains, allowed us to re-evaluate the codings of a few characters: in D. hantoniensis, the dentary symphysis extends from the posterior half of the fourth alveolus (BMNH 30397) to the center of the fifth alveolus (BMNH 30396, R1043); the surangular-articular suture is strongly bowed laterally within the glenoid fossa; the lateral
edges of the palatines are parallel posteriorly; the ectopterygoid-pterygoid flexure does not disappear
during ontogeny; and the quadratojugal-jugal suture lies at the posterior angle of the infratemporal fenestra. The result of these changes produced, however, a general polytomy of all the Diplocynodon species included in the analysis, indicating that further morphological data is needed to resolve the phylogenetic relationships of the species of this clade. MD supported by Synthesys (FR-TAF 967, BE-TAF 4907, GB-3097) and by the Spanish Ministerio de Economia y Competitividad (CGL2011-28681).
specimens of the Solitaire Pezophaps solitaria, the sister taxon of the Dodo Raphus cucullatus of neighbouring Mauritius.
Rodrigues Island has an extensive calcarenite plain in the southwest of the island, which contains numerous caves. A number
of expeditions explored the area and excavated the caves, especially during the 1860s and 1870s, resulting in the discovery of
thousands of subfossil bones. Some details of these activities were published, and some of the expedition explorers left
manuscript reports, all of which provide clues as to where they were excavating. Here, we present the results of a modern
attempt to reconstruct the movements of these expeditions and to discover which of the numerous caves were visited and
excavated.
excavated bones of the extinct fauna from caves in the vicinity. Stratigraphic description and radiocarbon dating revealed that sediments in Canyon Tiyel, a collapsed-cave feature, primarily accumulated during the early and middle Holocene. Sedimentation in the canyon and adjacent caves has slowed in recent millennia, with the result that many
bones of fauna that went extinct after human arrival in recent centuries are on or near the surface. The chemistry of the sediments and the alternate wet and dry regime of the cave and canyon surfaces are often not conducive to preservation of bone collagen and plant microfossils. Grotte Fougere, with an apparently unique anchialine pond inside a collapsing cave, however, contains over one meter of highly organic sediment with excellent preservation of plant and animal remains.
a decade ago providing different topologies according to the number of taxa included in the analysis and their degree of completeness. Here we present the result of the revision of the whole Hordwell Cliff collection hosted at the Natural History Museum in London. The study of several nearly complete, well-preserved skulls and lower jaws, as well as dozens of other cranial and postcranial remains, allowed us to re-evaluate the codings of a few characters: in D. hantoniensis, the dentary symphysis extends from the posterior half of the fourth alveolus (BMNH 30397) to the center of the fifth alveolus (BMNH 30396, R1043); the surangular-articular suture is strongly bowed laterally within the glenoid fossa; the lateral
edges of the palatines are parallel posteriorly; the ectopterygoid-pterygoid flexure does not disappear
during ontogeny; and the quadratojugal-jugal suture lies at the posterior angle of the infratemporal fenestra. The result of these changes produced, however, a general polytomy of all the Diplocynodon species included in the analysis, indicating that further morphological data is needed to resolve the phylogenetic relationships of the species of this clade. MD supported by Synthesys (FR-TAF 967, BE-TAF 4907, GB-3097) and by the Spanish Ministerio de Economia y Competitividad (CGL2011-28681).