Cyrille Delmer | University of Bath (original) (raw)

Papers by Cyrille Delmer

Research paper thumbnail of Ecological Transitions and the Shape of the Decapod Tree of Life

Integrative and Comparative Biology

Synopsis Understanding the processes that shaped the distribution of species richness across the ... more Synopsis Understanding the processes that shaped the distribution of species richness across the Tree of Life is a central macroevolutionary research agenda. Major ecological innovations, including transitions between habitats, may help to explain the striking asymmetries of diversity that are often observed between sister clades. Here, we test the impact of such transitions on speciation rates across decapod crustaceans, modeling diversification dynamics within a phylogenetic framework. Our results show that, while terrestrial lineages have higher speciation rates than either marine or freshwater lineages, there is no difference between mean speciation rates in marine and freshwater lineages across Decapoda. Partitioning our data by infraorder reveals that those clades with habitat heterogeneity have higher speciation rates in freshwater and terrestrial lineages, with freshwater rates up to 1.5 times faster than marine rates, and terrestrial rates approximately four times faster. T...

Research paper thumbnail of Climate Change and Extinction Risk in an Important Group of Marine Invertebrates (Decapoda): Inferences from the Geological Past

Research paper thumbnail of {"__content__"=>"Elevated atmospheric CO promoted speciation in mosquitoes (Diptera, Culicidae).", "sub"=>{"__content__"=>"2"}}

Communications biology, 2018

Mosquitoes are of great medical significance as vectors of deadly diseases. Despite this, little ... more Mosquitoes are of great medical significance as vectors of deadly diseases. Despite this, little is known about their evolutionary history or how their present day diversity has been shaped. Within a phylogenetic framework, here we show a strong correlation between climate change and mosquito speciation rates: the first time to our knowledge such an effect has been demonstrated for insects. Information theory reveals that although climate change is correlated with mosquito evolution there are other important factors at play. We identify one such driver to be the rise of mammals, which are predominant hosts of Culicidae. Regardless of the precise mechanism, we demonstrate a strong historical association. This finding, taken in combination with projected rises in atmospheric CO from anthropogenic activity, has important implications for culicid vector distributions and abundance, and consequently for human health.

Research paper thumbnail of Freshwater transitions and symbioses shaped the evolution and extant diversity of caridean shrimps

Communications biology, 2018

Understanding the processes that shaped the strikingly irregular distribution of species richness... more Understanding the processes that shaped the strikingly irregular distribution of species richness across the Tree of Life is a major research agenda. Changes in ecology may go some way to explain the often strongly asymmetrical fates of sister clades, and we test this in the caridean shrimps. First appearing in the Lower Jurassic, there are now ~3500 species worldwide. Carideans experienced several independent transitions to freshwater from marine habitats, while many of the marine species have also evolved a symbiotic lifestyle. Here we use diversification rate analyses to test whether these ecological traits promote or inhibit diversity within a phylogenetic framework. We demonstrate that speciation rates are more than twice as high in freshwater clades, whilst symbiotic ecologies are associated with lower speciation rates. These lower rates amongst symbiotic species are of concern given that symbioses often occur in some of the most diverse, delicately balanced and threatened mar...

Research paper thumbnail of Towards a Supertree of Arthropoda: A Species-Level Supertree of the Spiny, Slipper and Coral Lobsters (Decapoda: Achelata)

PLOS ONE, 2015

While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs... more While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy.

Research paper thumbnail of Book review - Urumaco and Venezuelan Paleontology: The Fossil Record of the Northern Neotropics. Edited by Marcelo Sanchez-Villagra, Orangel A. Aguilera, and Alfredo A. Carlini

Research paper thumbnail of Proboscidea

Paleontology and Geology of Laetoli: Human Evolution in Context, 2010

ABSTRACT Paleontological fieldwork between 1998–2005 by the Eyasi Plateau Expedition at Laetoli a... more ABSTRACT Paleontological fieldwork between 1998–2005 by the Eyasi Plateau Expedition at Laetoli and nearby sites produced a large collection of proboscidean fossils from the early to mid Pliocene Lower and Upper Laetolil Beds and late Pliocene Upper Ndolanya Beds, and possibly older sediments at Endolele, that substantially enlarges the sample of proboscidean material recovered earlier by Louis Leakey in 1935, Kohl-Larsen in 1938–1939, and Mary Leakey in the 1970s and early 1980s. The present study of the combined proboscidean sample confirms the presence of deinotheres and loxodont elephants, and provides the first description of anancine gomphotheres from the area. In addition, the first stegodont from the Eyasi Plateau is identified. The study also suggests that gomphotheres and loxodont elephants evolved locally in the Eyasi Plateau during the early Pliocene. Inference from stratigraphic distribution of proboscidean taxa, isotopic analyses, and dental morphology corresponds with paleoecological reconstruction depicting the Eyasi Plateau during the early-mid Pliocene as covered with abundant shrub- and grassland, with more restricted gallery forest, and as drier during the late Pliocene. Age-grade mortality profiles of elephants and deinotheres from the Laetolil and Upper Ndolanya Beds indicate a chronic lack of standing water or cyclical incidences of drought in the region for a sustained interval of time. KeywordsLaetoli-Endolele-Pliocene-Tanzania-Deinotheres-Loxodont elephants-Anancine gomphotheres

Research paper thumbnail of Towards a Supertree of Arthropoda: A Species-Level Supertree of the Spiny, Slipper and Coral Lobsters (Decapoda: Achelata)

PLOS ONE, 2015

While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs... more While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy.

Research paper thumbnail of IMC9-Deinotherium poster 20-07

Research paper thumbnail of The genus Arsinoitherium: catalogue of an unpublished collection of the Paris Natural History Museum and the problem of the number of species

Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Th... more Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Though one of the most represented prehistoric mammals in children's books, it is also one of the least well-known. Its unique morphology characterized by two enormous nasal horns and its singular teeth have fascinated palaeontologists for the last hundred years. Three species have been described to date: the type A. zitteli Beadnell 1902, the bigger and less common A. andrewsi Lankaster 1903 and the more recent A. giganteum Sanders 2004. Using the new and unpublished collection of Arsinoitherium from the Museum National d'Histoire Naturelle from Paris we studied the teeth and anatomy of this genus and realized that the criteria based on size used for the description of the different species are not reliable due to the great variability of measures taken mostly from the teeth. The taxonomic value of the species is questioned. There-fore we propose a new protocol of measure that cou...

Research paper thumbnail of El género Arsinoitherium: catálogo de la colección inédita del Muséum National d’Histoire Naturelle de París y el problema del número de especies

Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Th... more Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Though one of the most represented prehistoric mammals in children’s books, it is also one of the least well-known. Its unique morphology characterized by two enormous nasal horns and its singular teeth have fascinated palaeontologists for the last hundred years. Three species have been described to date: the type A. zitteli Beadnell 1902, the bigger and less common A. andrewsi Lankaster 1903 and the more recent A. giganteum Sanders 2004. Using the new and unpublished collection of Arsinoitherium from the Muséum National d’Histoire Naturelle from Paris we studied the teeth and anatomy of this genus and realized that the criteria based on size used for the description of the different species are not reliable due to the great variability of measures taken mostly from the teeth. The taxonomic value of the species is questioned. Therefore we propose a new protocol of measure that could help to solve the problem of the number of species within the genus Arsinoitherium.

Research paper thumbnail of The East Africa Oligocene intertrappean beds: Regional distribution, depositional environments and Afro/Arabian mammal dispersals

Journal of African Earth Sciences, Nov 2014

Continental “intertrappean” beds mark quiescence during Trap volcanic activity.Review and new dat... more Continental “intertrappean” beds mark quiescence during Trap volcanic activity.Review and new data from intertrappean beds in Eritrea, Ethiopia, Sudan, Arabia, Kenya.Age of intertrappean beds mostly encompassed between 29 and 27 Ma.Review of Mammal-bearing African localities in Oligocene intertrappean beds.Possible first occurrence of genus Prodeinotherium in the African fossil record.The extensive outpouring of the Oligocene Trap basalts over eastern Africa and western Arabia was interrupted by a period of quiescence marked by the deposition of terrestrial sediments. These so-called intertrappean beds are often lignitiferous and yield recurrent floras and faunas, sometimes represented by endemic mammals. We intended to highlight the peculiar features of these sedimentary intercalations using a large-scale approach including eastern Africa and the western Arabian peninsula.Starting from a new mapping in the Eritrean highland, the intertrappean beds resulted a continuous level that was a few tens of meters thick and traceable for some tens of kilometers. They consist of fluvial red, green and gray mudstones and siltstones with subordinate channelized pebbly sandstones, and lignite seams. Two new 40Ar–39Ar datings constraint the age of the intertrappean beds between 29.0 Ma and 23.6 Ma. The outcrops near Mendefera have yielded the remains of two proboscidean families, the Deinotheriidae and the Gomphoteriidae. The morphological grade of the two Mendefera proboscideans would suggest a more derived stage than that of representatives of the same families from other Oligocene African sites (e.g., Chilga, Ethiopia). An Oligocene age could be inferred for them. The occurrence of the genus Prodeinotherium at Mai Gobro possibly represents the first occurrence of this taxon, while the Gomphotheirum sp. might represent the oldest occurrence of this taxon in Africa before its dispersal towards Asia and Europe. Proboscideans have also been found in the lowland intertrappean beds of Dogali near Massawa. These sediments were contiguous with the Eritrean highland intertrappean beds during the Oligocene, but are now tectonically displaced from them by two thousand meters of vertical topographical distance. Dogali is also known for the occurrence of possible Deinotheriidae remains and the primitive elephantoid Eritreum. Entering the Ethiopian highland, an inspection of the Agere Selam (Mekele) intertrappean beds revealed the occurrence of lacustrine limestones and diatomites, which were contrastingly quite subordinate with respect to the fine clastic sediments found in the nearby Amba Alaji area. Further south, the intertrappean section in the Jema valley (100 km north of Addis Ababa and close to the Blue Nile gorge) is 120 m thick with predominant clastic sediments and a few diatomites at the top. Literature information from 35 additional sites, including northern Kenya, Yemen, Sudan and Saudi Arabia sections, confirms the fluvial and lacustrine depositional environment of the intertrappean beds, underlines the interest in their mammal fauna (Chilga, Losodok), and reports exploitable coal seams for some of them. As for the vegetal landscape in which the intertrappean beds were deposited, pollen and plant analysis results indicative of a tropical wet forest, similar to that of present-day western Africa. Another common feature of the intertrappean beds is their relatively limited thickness, averaging a few tens of meters, but reaching a few hundred meters in graben-related basins, such as Delbi Moye in southern Ethiopia. In most cases only thin, lens-shaped successions were deposited above the hummocky topography of their volcanic substratum, commonly unaffected by significant faulting. An average duration of the intertrappean beds is from one to three million years. This time interval is commonly matched by a few tens (or more rarely, hundreds) of meters of sediments left over after erosive episodes or depositional starvation. As to the lateral continuity of the intertrappean beds, the present-day outcrops show large differences: from some tens of kilometers in the Mendefera area, to a few tens of kilometres in the Jema valley, and to a few hundreds meters in the Agere Selam (Mekele) area. Even if it is difficult to quantify the original size of the sedimentation areas, it nevertheless proves that the intertrappean basins exceed thousands of square kilometers in only a single case (Mendefera), but were quite restricted in most cases. Their most likely endorheic and local character, together with a regional ill-defined fluvial network, was the effect of a water-course rerouting caused by the progressive rising of the eastern African and Arabian plateaux. Chronological constraints for the intertrappean beds can be inferred from the age of the hosting Trap succession and by the stratigraphical position that they occupy. Intervolcanic sedimentary episodes are typically found in the basaltic and subordinately rhyolitic successions that followed the 31–29 Ma old basaltic widespread paroxysm. With due caveats deriving from the discontinuous availability of datings specifically dedicated to this issue, we regard the age of the intertrappean beds as mostly encompassed in the interval from 29 to 27 Ma at the transition between the Early and Late Oligocene in the Ethiopia/Yemen Trap core. In marginal areas, such as SW Arabia, Eritrea and Kenya, the volcanic activity above the intertrappean beds resumed later, and its quiescence allowed a more prolonged period of sedimentation. The intertrappean beds fall in the second cooling event of the Oligocene climatic deterioration. During the contemporaneous apparent drop in the global sea-level and closure of the Tethyan Ocean between Arabia and southwestern Asia, connections were established between the African and the Eurasian continents. At that time, southwestern Asia was experiencing severe aridity with faunal exchanges toward the luxuriously vegetated eastern Africa.

Research paper thumbnail of Discovery of an embrithopod mammal (Arsinoitherium?) in the late Eocene of Tunisia

Journal of African Science, Nov 2013

We describe a new Paleogene fossil locality in Tunisia.New probable remains of the emblematic lar... more We describe a new Paleogene fossil locality in Tunisia.New probable remains of the emblematic large mammal Arsinoitherium are described.The enamel microstructure reveals affinities with derived Embrithopoda.Dental and postcranial remains (an atlas, carpus and metacarpus elements, and a part of the pelvic girdle) of an embrithopod mammal are described from Bir Om Ali, Tunisia, a new late Eocene locality. The enamel microstructure of a tooth fragment found in association shows ‘arsinoitheriid radial enamel’, an enamel condition which is characteristic of Arsinoitherium (Arsinoitheriidae, Embrithopoda). Although the postcranial elements slightly differ in size and morphology from those of Arsinoitherium zitteli (late Eocene to early Oligocene), we tentatively refer this new Eocene Tunisian material to that genus. These fossils represent the first known embrithopod from the Eocene of Tunisia.

Research paper thumbnail of Sir Hans Sloane and his fossils: a historical and scientific review of the first fossil collection of the British Museum

From Books to Bezoars: Sir Hans Sloan and His Collections, Oct 2012

Research paper thumbnail of From flat foot to fat foot: structure, ontogeny, function, and evolution of elephant “sixth toes”

Science, Dec 23, 2011

in the Doushantuo fossils [for example, opalinids are multinuclear (32)]. Only volvocalean embryo... more in the Doushantuo fossils [for example, opalinids are multinuclear (32)]. Only volvocalean embryos show so many rounds of palintomy, but the resulting blastomeres are connected by a system of cytoplasmic bridges (35) that are not present in the fossils. The combination of palintomy within a multilayered cyst wall and peanut-shaped germination stages as seen in the fossils conforms to the pattern seen in nonmetazoan holozoans; nonetheless, there are no discrete characters in the Doushantuo fossils that are uniquely holozoan. The "animal embryos" likely represent nonmetazoan holozoans or possibly even more distant eukaryote branches.

Research paper thumbnail of Book review - Urumaco and Venezuelan Paleontology: The Fossil Record of the Northern Neotropics. Edited by Marcelo Sanchez-Villagra, Orangel A. Aguilera, and Alfredo A. Carlini.

Research paper thumbnail of Finite element analysis: A promising tool for the reconstruction of extinct vertebrate graviportal taxa. A preliminary study based on the metacarpal arrangement of< i> Elephas maximus</i>

Comptes Rendus Palevol, Sep 2010

Research paper thumbnail of Proboscidea

Cenozoic Mammals of Africa, Jul 2010

... of the archaic elephants Primelephas korotorensis and Stegotetrabelodon orbus and the primiti... more ... of the archaic elephants Primelephas korotorensis and Stegotetrabelodon orbus and the primitive anancine gomphothere Anancus kenyensis (Sanders 1997) and Pleistocene horizons at Olduvai dominated by the more advanced elephant Elephas recki (Maglio 1973; Coppens ...

Research paper thumbnail of New Oligocene vertebrate localities from Northern Kenya (Turkana basin

Journal of Vertebrate Paleontology, Jan 2010

Research paper thumbnail of Reassessment of the Generic Attribution of Numidotherium savagei and the Homologies of Lower Incisors in Proboscideans

Acta Palaeontologica Polonica, Dec 2009

of the generic attribution of Numidotherium savagei and the homologies of lower incisors in probo... more of the generic attribution of Numidotherium savagei and the homologies of lower incisors in proboscideans. Acta Palaeontologica Polonica 54 (4): 561-580. doi:10.4202/app.2007.0036 Near the end of the twentieth century, a medium−sized early proboscidean found in Dor El Talha (late Eocene to early Oligocene), Libya, originally identified as a small species of Barytherium, was described as a new species of Numido− therium and designated Numidotherium savagei. Poorly known, this taxon has been excluded from most of the recent de− bate about the origin and diversification of the order Proboscidea. New specimens described herein show strong structural similarities of the upper teeth with those of bunolophodont early proboscideans (e.g., Moeritherium and Phiomia) and document the shared presence of derived traits in the postcranial skeleton. The newly referred material also demonstrates some unique characteristics of this taxon, notably in its mandibular morphology and the microstructure of its dental enamel. Included for the first time in a cladistic analysis (207 anatomical characters applied to all early tethytheres), N. savagei is distinct from both Numidotherium and Barytherium, and lies in an "intermediate" position between the strictly lophodont Eocene proboscideans and the bunolophodont moeritheres and elephantiforms. Accordingly, the species is herein referred to a new genus, Arcanotherium. New data on its mandibular symphysis and, especially, on its lower inci− sors loci and morphology, bring new support to a hypothesis of homology between the lower incisors of early proboscideans and the ever−growing lower tusks of the elephantiforms, which are identified here as di1 and i1.

Research paper thumbnail of Ecological Transitions and the Shape of the Decapod Tree of Life

Integrative and Comparative Biology

Synopsis Understanding the processes that shaped the distribution of species richness across the ... more Synopsis Understanding the processes that shaped the distribution of species richness across the Tree of Life is a central macroevolutionary research agenda. Major ecological innovations, including transitions between habitats, may help to explain the striking asymmetries of diversity that are often observed between sister clades. Here, we test the impact of such transitions on speciation rates across decapod crustaceans, modeling diversification dynamics within a phylogenetic framework. Our results show that, while terrestrial lineages have higher speciation rates than either marine or freshwater lineages, there is no difference between mean speciation rates in marine and freshwater lineages across Decapoda. Partitioning our data by infraorder reveals that those clades with habitat heterogeneity have higher speciation rates in freshwater and terrestrial lineages, with freshwater rates up to 1.5 times faster than marine rates, and terrestrial rates approximately four times faster. T...

Research paper thumbnail of Climate Change and Extinction Risk in an Important Group of Marine Invertebrates (Decapoda): Inferences from the Geological Past

Research paper thumbnail of {"__content__"=>"Elevated atmospheric CO promoted speciation in mosquitoes (Diptera, Culicidae).", "sub"=>{"__content__"=>"2"}}

Communications biology, 2018

Mosquitoes are of great medical significance as vectors of deadly diseases. Despite this, little ... more Mosquitoes are of great medical significance as vectors of deadly diseases. Despite this, little is known about their evolutionary history or how their present day diversity has been shaped. Within a phylogenetic framework, here we show a strong correlation between climate change and mosquito speciation rates: the first time to our knowledge such an effect has been demonstrated for insects. Information theory reveals that although climate change is correlated with mosquito evolution there are other important factors at play. We identify one such driver to be the rise of mammals, which are predominant hosts of Culicidae. Regardless of the precise mechanism, we demonstrate a strong historical association. This finding, taken in combination with projected rises in atmospheric CO from anthropogenic activity, has important implications for culicid vector distributions and abundance, and consequently for human health.

Research paper thumbnail of Freshwater transitions and symbioses shaped the evolution and extant diversity of caridean shrimps

Communications biology, 2018

Understanding the processes that shaped the strikingly irregular distribution of species richness... more Understanding the processes that shaped the strikingly irregular distribution of species richness across the Tree of Life is a major research agenda. Changes in ecology may go some way to explain the often strongly asymmetrical fates of sister clades, and we test this in the caridean shrimps. First appearing in the Lower Jurassic, there are now ~3500 species worldwide. Carideans experienced several independent transitions to freshwater from marine habitats, while many of the marine species have also evolved a symbiotic lifestyle. Here we use diversification rate analyses to test whether these ecological traits promote or inhibit diversity within a phylogenetic framework. We demonstrate that speciation rates are more than twice as high in freshwater clades, whilst symbiotic ecologies are associated with lower speciation rates. These lower rates amongst symbiotic species are of concern given that symbioses often occur in some of the most diverse, delicately balanced and threatened mar...

Research paper thumbnail of Towards a Supertree of Arthropoda: A Species-Level Supertree of the Spiny, Slipper and Coral Lobsters (Decapoda: Achelata)

PLOS ONE, 2015

While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs... more While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy.

Research paper thumbnail of Book review - Urumaco and Venezuelan Paleontology: The Fossil Record of the Northern Neotropics. Edited by Marcelo Sanchez-Villagra, Orangel A. Aguilera, and Alfredo A. Carlini

Research paper thumbnail of Proboscidea

Paleontology and Geology of Laetoli: Human Evolution in Context, 2010

ABSTRACT Paleontological fieldwork between 1998–2005 by the Eyasi Plateau Expedition at Laetoli a... more ABSTRACT Paleontological fieldwork between 1998–2005 by the Eyasi Plateau Expedition at Laetoli and nearby sites produced a large collection of proboscidean fossils from the early to mid Pliocene Lower and Upper Laetolil Beds and late Pliocene Upper Ndolanya Beds, and possibly older sediments at Endolele, that substantially enlarges the sample of proboscidean material recovered earlier by Louis Leakey in 1935, Kohl-Larsen in 1938–1939, and Mary Leakey in the 1970s and early 1980s. The present study of the combined proboscidean sample confirms the presence of deinotheres and loxodont elephants, and provides the first description of anancine gomphotheres from the area. In addition, the first stegodont from the Eyasi Plateau is identified. The study also suggests that gomphotheres and loxodont elephants evolved locally in the Eyasi Plateau during the early Pliocene. Inference from stratigraphic distribution of proboscidean taxa, isotopic analyses, and dental morphology corresponds with paleoecological reconstruction depicting the Eyasi Plateau during the early-mid Pliocene as covered with abundant shrub- and grassland, with more restricted gallery forest, and as drier during the late Pliocene. Age-grade mortality profiles of elephants and deinotheres from the Laetolil and Upper Ndolanya Beds indicate a chronic lack of standing water or cyclical incidences of drought in the region for a sustained interval of time. KeywordsLaetoli-Endolele-Pliocene-Tanzania-Deinotheres-Loxodont elephants-Anancine gomphotheres

Research paper thumbnail of Towards a Supertree of Arthropoda: A Species-Level Supertree of the Spiny, Slipper and Coral Lobsters (Decapoda: Achelata)

PLOS ONE, 2015

While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs... more While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy.

Research paper thumbnail of IMC9-Deinotherium poster 20-07

Research paper thumbnail of The genus Arsinoitherium: catalogue of an unpublished collection of the Paris Natural History Museum and the problem of the number of species

Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Th... more Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Though one of the most represented prehistoric mammals in children's books, it is also one of the least well-known. Its unique morphology characterized by two enormous nasal horns and its singular teeth have fascinated palaeontologists for the last hundred years. Three species have been described to date: the type A. zitteli Beadnell 1902, the bigger and less common A. andrewsi Lankaster 1903 and the more recent A. giganteum Sanders 2004. Using the new and unpublished collection of Arsinoitherium from the Museum National d'Histoire Naturelle from Paris we studied the teeth and anatomy of this genus and realized that the criteria based on size used for the description of the different species are not reliable due to the great variability of measures taken mostly from the teeth. The taxonomic value of the species is questioned. There-fore we propose a new protocol of measure that cou...

Research paper thumbnail of El género Arsinoitherium: catálogo de la colección inédita del Muséum National d’Histoire Naturelle de París y el problema del número de especies

Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Th... more Arsinoitherium is one of the most emblematic genera from the fossil fauna of African Tertiary. Though one of the most represented prehistoric mammals in children’s books, it is also one of the least well-known. Its unique morphology characterized by two enormous nasal horns and its singular teeth have fascinated palaeontologists for the last hundred years. Three species have been described to date: the type A. zitteli Beadnell 1902, the bigger and less common A. andrewsi Lankaster 1903 and the more recent A. giganteum Sanders 2004. Using the new and unpublished collection of Arsinoitherium from the Muséum National d’Histoire Naturelle from Paris we studied the teeth and anatomy of this genus and realized that the criteria based on size used for the description of the different species are not reliable due to the great variability of measures taken mostly from the teeth. The taxonomic value of the species is questioned. Therefore we propose a new protocol of measure that could help to solve the problem of the number of species within the genus Arsinoitherium.

Research paper thumbnail of The East Africa Oligocene intertrappean beds: Regional distribution, depositional environments and Afro/Arabian mammal dispersals

Journal of African Earth Sciences, Nov 2014

Continental “intertrappean” beds mark quiescence during Trap volcanic activity.Review and new dat... more Continental “intertrappean” beds mark quiescence during Trap volcanic activity.Review and new data from intertrappean beds in Eritrea, Ethiopia, Sudan, Arabia, Kenya.Age of intertrappean beds mostly encompassed between 29 and 27 Ma.Review of Mammal-bearing African localities in Oligocene intertrappean beds.Possible first occurrence of genus Prodeinotherium in the African fossil record.The extensive outpouring of the Oligocene Trap basalts over eastern Africa and western Arabia was interrupted by a period of quiescence marked by the deposition of terrestrial sediments. These so-called intertrappean beds are often lignitiferous and yield recurrent floras and faunas, sometimes represented by endemic mammals. We intended to highlight the peculiar features of these sedimentary intercalations using a large-scale approach including eastern Africa and the western Arabian peninsula.Starting from a new mapping in the Eritrean highland, the intertrappean beds resulted a continuous level that was a few tens of meters thick and traceable for some tens of kilometers. They consist of fluvial red, green and gray mudstones and siltstones with subordinate channelized pebbly sandstones, and lignite seams. Two new 40Ar–39Ar datings constraint the age of the intertrappean beds between 29.0 Ma and 23.6 Ma. The outcrops near Mendefera have yielded the remains of two proboscidean families, the Deinotheriidae and the Gomphoteriidae. The morphological grade of the two Mendefera proboscideans would suggest a more derived stage than that of representatives of the same families from other Oligocene African sites (e.g., Chilga, Ethiopia). An Oligocene age could be inferred for them. The occurrence of the genus Prodeinotherium at Mai Gobro possibly represents the first occurrence of this taxon, while the Gomphotheirum sp. might represent the oldest occurrence of this taxon in Africa before its dispersal towards Asia and Europe. Proboscideans have also been found in the lowland intertrappean beds of Dogali near Massawa. These sediments were contiguous with the Eritrean highland intertrappean beds during the Oligocene, but are now tectonically displaced from them by two thousand meters of vertical topographical distance. Dogali is also known for the occurrence of possible Deinotheriidae remains and the primitive elephantoid Eritreum. Entering the Ethiopian highland, an inspection of the Agere Selam (Mekele) intertrappean beds revealed the occurrence of lacustrine limestones and diatomites, which were contrastingly quite subordinate with respect to the fine clastic sediments found in the nearby Amba Alaji area. Further south, the intertrappean section in the Jema valley (100 km north of Addis Ababa and close to the Blue Nile gorge) is 120 m thick with predominant clastic sediments and a few diatomites at the top. Literature information from 35 additional sites, including northern Kenya, Yemen, Sudan and Saudi Arabia sections, confirms the fluvial and lacustrine depositional environment of the intertrappean beds, underlines the interest in their mammal fauna (Chilga, Losodok), and reports exploitable coal seams for some of them. As for the vegetal landscape in which the intertrappean beds were deposited, pollen and plant analysis results indicative of a tropical wet forest, similar to that of present-day western Africa. Another common feature of the intertrappean beds is their relatively limited thickness, averaging a few tens of meters, but reaching a few hundred meters in graben-related basins, such as Delbi Moye in southern Ethiopia. In most cases only thin, lens-shaped successions were deposited above the hummocky topography of their volcanic substratum, commonly unaffected by significant faulting. An average duration of the intertrappean beds is from one to three million years. This time interval is commonly matched by a few tens (or more rarely, hundreds) of meters of sediments left over after erosive episodes or depositional starvation. As to the lateral continuity of the intertrappean beds, the present-day outcrops show large differences: from some tens of kilometers in the Mendefera area, to a few tens of kilometres in the Jema valley, and to a few hundreds meters in the Agere Selam (Mekele) area. Even if it is difficult to quantify the original size of the sedimentation areas, it nevertheless proves that the intertrappean basins exceed thousands of square kilometers in only a single case (Mendefera), but were quite restricted in most cases. Their most likely endorheic and local character, together with a regional ill-defined fluvial network, was the effect of a water-course rerouting caused by the progressive rising of the eastern African and Arabian plateaux. Chronological constraints for the intertrappean beds can be inferred from the age of the hosting Trap succession and by the stratigraphical position that they occupy. Intervolcanic sedimentary episodes are typically found in the basaltic and subordinately rhyolitic successions that followed the 31–29 Ma old basaltic widespread paroxysm. With due caveats deriving from the discontinuous availability of datings specifically dedicated to this issue, we regard the age of the intertrappean beds as mostly encompassed in the interval from 29 to 27 Ma at the transition between the Early and Late Oligocene in the Ethiopia/Yemen Trap core. In marginal areas, such as SW Arabia, Eritrea and Kenya, the volcanic activity above the intertrappean beds resumed later, and its quiescence allowed a more prolonged period of sedimentation. The intertrappean beds fall in the second cooling event of the Oligocene climatic deterioration. During the contemporaneous apparent drop in the global sea-level and closure of the Tethyan Ocean between Arabia and southwestern Asia, connections were established between the African and the Eurasian continents. At that time, southwestern Asia was experiencing severe aridity with faunal exchanges toward the luxuriously vegetated eastern Africa.

Research paper thumbnail of Discovery of an embrithopod mammal (Arsinoitherium?) in the late Eocene of Tunisia

Journal of African Science, Nov 2013

We describe a new Paleogene fossil locality in Tunisia.New probable remains of the emblematic lar... more We describe a new Paleogene fossil locality in Tunisia.New probable remains of the emblematic large mammal Arsinoitherium are described.The enamel microstructure reveals affinities with derived Embrithopoda.Dental and postcranial remains (an atlas, carpus and metacarpus elements, and a part of the pelvic girdle) of an embrithopod mammal are described from Bir Om Ali, Tunisia, a new late Eocene locality. The enamel microstructure of a tooth fragment found in association shows ‘arsinoitheriid radial enamel’, an enamel condition which is characteristic of Arsinoitherium (Arsinoitheriidae, Embrithopoda). Although the postcranial elements slightly differ in size and morphology from those of Arsinoitherium zitteli (late Eocene to early Oligocene), we tentatively refer this new Eocene Tunisian material to that genus. These fossils represent the first known embrithopod from the Eocene of Tunisia.

Research paper thumbnail of Sir Hans Sloane and his fossils: a historical and scientific review of the first fossil collection of the British Museum

From Books to Bezoars: Sir Hans Sloan and His Collections, Oct 2012

Research paper thumbnail of From flat foot to fat foot: structure, ontogeny, function, and evolution of elephant “sixth toes”

Science, Dec 23, 2011

in the Doushantuo fossils [for example, opalinids are multinuclear (32)]. Only volvocalean embryo... more in the Doushantuo fossils [for example, opalinids are multinuclear (32)]. Only volvocalean embryos show so many rounds of palintomy, but the resulting blastomeres are connected by a system of cytoplasmic bridges (35) that are not present in the fossils. The combination of palintomy within a multilayered cyst wall and peanut-shaped germination stages as seen in the fossils conforms to the pattern seen in nonmetazoan holozoans; nonetheless, there are no discrete characters in the Doushantuo fossils that are uniquely holozoan. The "animal embryos" likely represent nonmetazoan holozoans or possibly even more distant eukaryote branches.

Research paper thumbnail of Book review - Urumaco and Venezuelan Paleontology: The Fossil Record of the Northern Neotropics. Edited by Marcelo Sanchez-Villagra, Orangel A. Aguilera, and Alfredo A. Carlini.

Research paper thumbnail of Finite element analysis: A promising tool for the reconstruction of extinct vertebrate graviportal taxa. A preliminary study based on the metacarpal arrangement of< i> Elephas maximus</i>

Comptes Rendus Palevol, Sep 2010

Research paper thumbnail of Proboscidea

Cenozoic Mammals of Africa, Jul 2010

... of the archaic elephants Primelephas korotorensis and Stegotetrabelodon orbus and the primiti... more ... of the archaic elephants Primelephas korotorensis and Stegotetrabelodon orbus and the primitive anancine gomphothere Anancus kenyensis (Sanders 1997) and Pleistocene horizons at Olduvai dominated by the more advanced elephant Elephas recki (Maglio 1973; Coppens ...

Research paper thumbnail of New Oligocene vertebrate localities from Northern Kenya (Turkana basin

Journal of Vertebrate Paleontology, Jan 2010

Research paper thumbnail of Reassessment of the Generic Attribution of Numidotherium savagei and the Homologies of Lower Incisors in Proboscideans

Acta Palaeontologica Polonica, Dec 2009

of the generic attribution of Numidotherium savagei and the homologies of lower incisors in probo... more of the generic attribution of Numidotherium savagei and the homologies of lower incisors in proboscideans. Acta Palaeontologica Polonica 54 (4): 561-580. doi:10.4202/app.2007.0036 Near the end of the twentieth century, a medium−sized early proboscidean found in Dor El Talha (late Eocene to early Oligocene), Libya, originally identified as a small species of Barytherium, was described as a new species of Numido− therium and designated Numidotherium savagei. Poorly known, this taxon has been excluded from most of the recent de− bate about the origin and diversification of the order Proboscidea. New specimens described herein show strong structural similarities of the upper teeth with those of bunolophodont early proboscideans (e.g., Moeritherium and Phiomia) and document the shared presence of derived traits in the postcranial skeleton. The newly referred material also demonstrates some unique characteristics of this taxon, notably in its mandibular morphology and the microstructure of its dental enamel. Included for the first time in a cladistic analysis (207 anatomical characters applied to all early tethytheres), N. savagei is distinct from both Numidotherium and Barytherium, and lies in an "intermediate" position between the strictly lophodont Eocene proboscideans and the bunolophodont moeritheres and elephantiforms. Accordingly, the species is herein referred to a new genus, Arcanotherium. New data on its mandibular symphysis and, especially, on its lower inci− sors loci and morphology, bring new support to a hypothesis of homology between the lower incisors of early proboscideans and the ever−growing lower tusks of the elephantiforms, which are identified here as di1 and i1.