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Rodolphe Tabuce - One of the best experts on this subject based on the ideXlab platform.
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A dwarf among giants: Titanohyrax tantulus (Hyracoidea, Mammalia) from the Eocene of Chambi, Tunisia and Glib Zegdou, Algeria
2018Co-Authors: Rodolphe Tabuce, Mohammed Adaci, Hayet Khayati Ammar, Mustapha Bensalah, Essid Mabrouk, Wissem Marzougui, Fateh Mebrouk, Laurent Marivaux, Rim TemaniAbstract:The Hyracoidea was a successful mammalian order in Africa from the early Eocene to the mid-Miocene. Through the Eocene/Oligocene, hyracoids represented the dominant 'ungulate' group in terrestrial ecosystems. Among them, the genus Titanohyrax embraces very large species as well as a small one, T. tantulus, only known from the ?early/middle Eocene of Chambi, Tunisia. Recently, the generic affinity of this species has been disputed, implying a latest Eocene origin for Titanohyrax. Testing the competing hypotheses requires new data as most species of Titanohyrax are documented by few specimens. Based on new fossils from Chambi and CT scan analysis of the holotype, we revised T. tantulus. A complete skull from the coeval locality Glib Zegdou, Algeria, is also discussed. This analysis reveals that the holotype bears a part of dP3-4 and M1-2 rather than dP2-M1 as it was proposed. More importantly, derived dental characters, including a small compressed hypocone on P2-M3 and highly molarized P3-4 with a W-shaped ectoloph, are distinctive features of Titanohyracidae. Enamel microstructure also indicates affinities with the titanohyracids Antilohyrax and Afrohyrax. Titanohyrax tantulus and Antilohyrax also share a tall, narrow and vertically oriented supraoccipital and no diastemata between the anterior teeth. Moreover, the lack of postorbital bar, a well-developed metastylid on p3-m3, and broad spatulate lower incisors, that lacked tines or serrations, are diagnostic characters of Titanohyrax. As a result, there is no apparent reason to question the generic affinity of T. tantulus. However, the latter differs substantially from the other species of the genus, in harboring a suite of primitive characters: lower crowned cheek teeth, absence of mesostyle on P1-2, less labially expanded mesostyle and parastyle on P4-M3, more labially positioned paracone and metacone, blunt parastyle and mesostyle, longer preprotocrista and prehypocrista, and presence of a paraconular swelling on molars. Titanohyrax tantulus finally differs from late Eocene titanohyracids (Antilohyrax and Titanohyrax sp.) in having sharp supraorbital ridge and extensive sagittal crest, certainly also primitive cranial characters. To conclude, T. tantulus represents an early offshoot of the titanohyracids; this family thus testifies to the longest fossil record among hyracoids. It only disappeared during the early Miocene, likely due to competition with artiodactyls and perissodactyls. * Speaker
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de l ombre aux lumieres et reciproquement redecouverte du crâne de procavia capensis pallas 1766 Hyracoidea mammalia decrit en 1767 par daubenton dans l histoire naturelle
Zoosystema, 2017Co-Authors: Rodolphe Tabuce, Stephane SchmittAbstract:From darkness to Enlightenment, and vice versa: rediscovery of the skull of Procavia capensis (Pallas, 1766) (Hyracoidea, Mammalia) described in 1767 by Daubenton in the Histoire naturelle.A skull of Procavia capensis (Pallas, 1766) (Hyracoidea, Mammalia), currently on display in the Galerie de Paleontologie et d'Anatomie comparee (Paleontology and comparative Anatomy Gallery) of the Museum national d'Histoire naturelle, Paris, is here identified as the one Daubenton described in 1767 in the catalog of the viviparous quadruped collections of the King's Cabinet he wrote for Buffon's Histoire naturelle (Natural History). While Daubenton clearly recognized in this skull from Sidon, Lebanon, the most remarkable characters of hyracoids, especially the teeth, he could not identify the animal, since the first precise description of the species was published by Pallas at the same time (at the end of 1766). In subsequent volumes of the Histoire naturelle, Buffon repeatedly dealt with the hyrax, on the basis of new data, but he failed to assign the skull of Sidon to this species, although Pallas recognized the nature of this skull as early as 1776. In a volume of the Histoire naturelle published in 1789, after Buffon's death, this skull was illustrated on a plate and considered as belonging to a primate, the Bengal slow loris (Nycticebus bengalensis (Lacepede, 1800)). Fifteen years later, it was one of the specimens which enabled Cuvier to remove the hyrax from the order Glires or Rodents, in which it was generally placed since Pallas, to assign it to the Pachydermes.
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Dental Eruption and Growth in Hyracoidea (Mammalia, Afrotheria)
Journal of Vertebrate Paleontology, 2017Co-Authors: Robert J. Asher, Rodolphe Tabuce, Erik R. Seiffert, Gf Gunnell, David Pattinson, Hesham M. SallamAbstract:ABSTRACT We investigated dental homologies, development, and growth in living and fossil hyracoids and tested if hyracoids and other mammals show correlations between eruption patterns, gestation time, and age at maturity. Unlike living species, fossil hyracoids simultaneously possess replaced P1 and canine teeth. Fossil species also have shorter crowns, an I3/i3, I2, and a hypoconulid on m3. Prenatal specimens of the living Procavia capensis and Heterohyrax brucei show up to three tooth buds posterior to dI1 and anterior to the seven upper cheek teeth that consistently erupt; erupted teeth include an anterior premolar but not a canine. Most lower cheek teeth finish eruption during growth in hyracoids, not after growth as in most other afrotherians. All hyracoids show the m1 at (lower) or near (upper) the beginning of eruption of permanent teeth; M3/m3 is the last permanent tooth to erupt. The living P. capensis erupts most lower antemolar loci before m2. In contrast, fossil hyraxes erupt lower antemolars...
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Dental eruption and growth in Hyracoidea (Mammalia, Afrotheria)
2017Co-Authors: Robert J. Asher, Rodolphe Tabuce, Erik R. Seiffert, Gf Gunnell, David Pattinson, Hesham M. SallamAbstract:We investigated dental homologies, development, and growth in living and fossil hyracoids and tested if hyracoids and other mammals show correlations between eruption patterns, gestation time, and age at maturity. Unlike living species, fossil hyracoids simultaneously possess replaced P1 and canine teeth. Fossil species also have shorter crowns, an I3/i3, I2, and a hypoconulid on m3. Prenatal specimens of the living Procavia capensis and Heterohyrax brucei show up to three tooth buds posterior to dI1 and anterior to the seven upper cheek teeth that consistently erupt; erupted teeth include an anterior premolar but not a canine. Most lower cheek teeth finish eruption during growth in hyracoids, not after growth as in most other afrotherians. All hyracoids show the m1 at (lower) or near (upper) the beginning of eruption of permanent teeth; M3/m3 is the last permanent tooth to erupt. The living P. capensis erupts most lower antemolar loci before m2. In contrast, fossil hyraxes erupt lower antemolars after m2. Although the early eruption of antemolars correlates with increased gestation time and age at maturity in primates and Tupaia (i.e., ‘Schultz's rule’), and although modern hyraxes resemble some anthropoid primates in exhibiting long gestation and eruption of antemolars at or before molars, eruption patterns do not significantly covary with either life history parameter among afrotherians sampled so far. However, we do observe a shift in eruption timing and crown height in Procavia relative to fossil hyracoids, mirroring observations recently made for other ungulate-grade mammals. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Asher, R. J., G. F. Gunnell, E. R. Seiffert, D. Pattinson, R. Tabuce, L. Hautier, and H. M. Sallam. 2017. Dental eruption and growth in Hyracoidea (Mammalia, Afrotheria). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1317638.
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new material of seggeurius amourensis paenungulata Hyracoidea including a partial skull with intact basicranium
Journal of Vertebrate Paleontology, 2016Co-Authors: Julien Benoit, Mohammed Adaci, Mustapha Bensalah, Jean-yves Crochet, Mohammed Mahboubi, Jean-jacques Jaeger, Rodolphe TabuceAbstract:ABSTRACTSeggeurius is the basal-most hyracoid known to date, and one of the earliest known fossil afrotherians. This taxon has a dramatic importance in mammalian phylogeny, but until now it was known from dental remains only. Here we describe previously unpublished material of Seggeurius, including some mandibular and maxillary fragments, and a braincase. This study is the first to thoroughly describe and discuss the morphology of the ear region and osseous inner ear of a Paleogene hyracoid. It allows a reappraisal of some important characters that are often used in cladistic analyses of Paenungulata. In particular, it seems that in stem hyracoids the orbit is located caudally, the eustachian sac is absent or reduced, the course of the internal carotid artery is intrabullar and medial, and a deep epitympanic sinus, a basisphenoid contribution to the bulla, and the stapedial artery are present. The cochlear canal is rather flattened, and the secondary common crus was rapidly lost. A cladistic analysis of s...
Julien Benoit - One of the best experts on this subject based on the ideXlab platform.
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new material of seggeurius amourensis paenungulata Hyracoidea including a partial skull with intact basicranium
Journal of Vertebrate Paleontology, 2016Co-Authors: Julien Benoit, Mohammed Adaci, Mustapha Bensalah, Jean-yves Crochet, Mohammed Mahboubi, Jean-jacques Jaeger, Rodolphe TabuceAbstract:ABSTRACTSeggeurius is the basal-most hyracoid known to date, and one of the earliest known fossil afrotherians. This taxon has a dramatic importance in mammalian phylogeny, but until now it was known from dental remains only. Here we describe previously unpublished material of Seggeurius, including some mandibular and maxillary fragments, and a braincase. This study is the first to thoroughly describe and discuss the morphology of the ear region and osseous inner ear of a Paleogene hyracoid. It allows a reappraisal of some important characters that are often used in cladistic analyses of Paenungulata. In particular, it seems that in stem hyracoids the orbit is located caudally, the eustachian sac is absent or reduced, the course of the internal carotid artery is intrabullar and medial, and a deep epitympanic sinus, a basisphenoid contribution to the bulla, and the stapedial artery are present. The cochlear canal is rather flattened, and the secondary common crus was rapidly lost. A cladistic analysis of s...
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New material of Seggeurius amourensis (Paenungulata, Hyracoidea), including a partial skull with intact basicranium
2015Co-Authors: Julien Benoit, Mohammed Adaci, Mustapha Bensalah, Jean-yves Crochet, Mohammed Mahboubi, Jean-jacques Jaeger, Rodolphe TabuceAbstract:Seggeurius is the basal-most hyracoid known to date, and one of the earliest known fossil afrotherians. This taxon has a dramatic importance in mammalian phylogeny, but until now it was known from dental remains only. Here we describe previously unpublished material of Seggeurius, including some mandibular and maxillary fragments, and a braincase. This study is the first to thoroughly describe and discuss the morphology of the ear region and osseous inner ear of a Paleogene hyracoid. It allows a reappraisal of some important characters that are often used in cladistic analyses of Paenungulata. In particular, it seems that in stem hyracoids the orbit is located caudally, the eustachian sac is absent or reduced, the course of the internal carotid artery is intrabullar and medial, and a deep epitympanic sinus, a basisphenoid contribution to the bulla, and the stapedial artery are present. The cochlear canal is rather flattened, and the secondary common crus was rapidly lost. A cladistic analysis of stem placental mammals highlights three derived traits shared by Seggeurius and stem sirenians (the tuber-shaped postglenoid process, the squared and massive mastoid apophysis of the petrosal, and the presence of a swelling on the septum metacochleare) and supports molecular analysis that hypothesizes a Hyracoidea-Sirenia sister-group relationship. This study demonstrates how useful the petrosal and labyrinthine characters of fossils can be for mammalian phylogenetic inference. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Benoit, J., J.-Y. Crochet, M. Mahboubi, J.-J. Jaeger, M. Bensalah, M. Adaci, and R. Tabuce. 2015. New material of Seggeurius amourensis (Paenungulata, Hyracoidea), including a partial skull with intact basicranium. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1034358.
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evolution des caracteres crâniens et endocrâniens chez les afrotheria mammalia et phylogenie du groupe
2013Co-Authors: Julien BenoitAbstract:L'etude des caracteres basicrâniens et endocraniens chez les vertebres fossiles et actuels connait un regain d'interet depuis quelques annees. Ces caracteres beneficient en effet d'une bonne reputation en tant que marqueurs phylogenetiques, ainsi que d'un biais taphonomique favorable a leur fossilisation. C'est pourquoi dans ce volume, la region auditive et l'oreille interne (Partie I) et l'endocrâne (Partie II) de mammiferes fossiles appartenant au clade des Afrotheria ont ete scannes par (micro)tomographie a rayon-X, decrits, etudies et compares a ceux des especes actuelles. Il s'agit plus precisement des Afrotheria fossiles que sont les Bibymalagasia (Chapitre 1), le Macroscelididae Chambius (Chapitre 2), de nombreux Hyracoidea du Paleogene (Chapitre 3) ainsi que des Tethytheria basaux tels que le proboscidien Numidotherium, l'embrithopode Arsinoitherium et le sirenien Prorastomus (Chapitre 4). Cette etude met en lumiere l'interessant signal phylogenetique fournit par les caracteres de la region auditive et de l'endocrâne, capable de soutenir certains clades moleculaires (e.g. Afroinsectivora, ‘Panelephantulus'). Elle montre aussi comment, sous certaines pressions de selection, ces caracteres peuvent converger de facon remarquable (e.g. chez les tethytheres). Cette etude apporte aussi des elements qui appuient l'hypothese d'une origine Africaine des Afrotheria, ainsi que celle faisant de l'ancetre commun des afrotheres un mammifere plutot ‘ongule' que ‘insectivore'. Ces inferences fondees sur l'observation des representants fossiles les plus anciens de ce groupe sont importants pour notre comprehension de l'origine et de la diversification des afrotheres et des mammiferes placentaires en general.
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Cranial Remain from Tunisia Provides New Clues for the Origin and Evolution of Sirenia (Mammalia, Afrotheria) in Africa
PloS one, 2013Co-Authors: Julien Benoit, Laurent Marivaux, Sylvain Adnet, Essid El Mabrouk, Hayet Khayati, Mustapha Ben Haj Ali, Gilles Merzeraud, Samuel Merigeaud, Monique Vianey-liaud, Rodolphe TabuceAbstract:Sea cows (manatees, dugongs) are the only living marine mammals to feed solely on aquatic plants. Unlike whales or dolphins (Cetacea), the earliest evolutionary history of sirenians is poorly documented, and limited to a few fossils including skulls and skeletons of two genera composing the stem family of Prorastomidae (Prorastomus and Pezosiren). Surprisingly, these fossils come from the Eocene of Jamaica, while stem Hyracoidea and Proboscidea - the putative sister-groups to Sirenia - are recorded in Africa as early as the Late Paleocene. So far, the historical biogeography of early Sirenia has remained obscure given this paradox between phylogeny and fossil record. Here we use X-ray microtomography to investigate a newly discovered sirenian petrosal from the Eocene of Tunisia. This fossil represents the oldest occurrence of sirenians in Africa. The morphology of this petrosal is more primitive than the Jamaican prorastomids’ one, which emphasizes the basal position of this new African taxon within the Sirenia clade. This discovery testifies to the great antiquity of Sirenia in Africa, and therefore supports their African origin. While isotopic analyses previously suggested sirenians had adapted directly to the marine environment, new paleoenvironmental evidence suggests that basal-most sea cows were likely restricted to fresh waters.
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Cranial Remain from Tunisia Provides New Clues for the Origin and Evolution of Sirenia (Mammalia, Afrotheria) in Africa
2013Co-Authors: Julien Benoit, Laurent Marivaux, Sylvain Adnet, Essid El Mabrouk, Hayet Khayati, Gilles Merzeraud, Samuel Merigeaud, Mustapha Ben, Haj Ali, Monique Vianey-liaudAbstract:Sea cows (manatees, dugongs) are the only living marine mammals to feed solely on aquatic plants. Unlike whales or dolphins (Cetacea), the earliest evolutionary history of sirenians is poorly documented, and limited to a few fossils including skulls and skeletons of two genera composing the stem family of Prorastomidae (Prorastomus and Pezosiren). Surprisingly, these fossils come from the Eocene of Jamaica, while stem Hyracoidea and Proboscidea- the putative sister-groups to Sirenia- are recorded in Africa as early as the Late Paleocene. So far, the historical biogeography of early Sirenia has remained obscure given this paradox between phylogeny and fossil record. Here we use X-ray microtomography to investigate a newly discovered sirenian petrosal from the Eocene of Tunisia. This fossil represents the oldest occurrence of sirenians in Africa. The morphology of this petrosal is more primitive than the Jamaican prorastomids ’ one, which emphasizes the basal position of this new African taxon within the Sirenia clade. This discovery testifies to the great antiquity of Sirenia in Africa, and therefore supports their African origin. While isotopic analyses previously suggested sirenians had adapted directly to the marine environment, new paleoenvironmental evidence suggests that basal-most se
Ulrich Welsch - One of the best experts on this subject based on the ideXlab platform.
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Cutaneous Eccrine Glands of the Foot Pads of the Rock Hyrax (Procavia capensis, Hyracoidea, Mammalia)
Cells tissues organs, 2002Co-Authors: Peter Stumpf, Ulrich WelschAbstract:In order to find correlations between skin gland morphology and specific ethological features, the cutaneous glands of the foot pads of Procavia capensis were studied by histological and various histochemical methods and by electron microscopy. In the foot pads, abundant specific eccrine skin glands occur, which consist of coiled tubular secretory portions and coiled ducts. The wall of the secretory part is composed of cuboidal glandular cells and myoepithelial cells. Among the glandular cells two types occur: clear and dark cells. Clear cells have numerous mitochondria and form a basal labyrinth, indicating fluid transport. Dark cells, which stain strongly with periodic acid-Schiff, contain a highly developed perinuclear Golgi apparatus, large amounts of rough endoplasmic reticulum and many secretory granules indicating production of glycoproteins. Cytokeratin (CK) 19 was found in secretory compartments and ducts, CK14 only in duct cells. Single cells of the secretory coils and ducts may be stained with antibodies against antimicrobial peptides. Some glandular cells contain proliferating cell nuclear antigen-positive nuclei especially in the ducts indicating an increased cell proliferation. Terminal transferase (TdT)-mediated d-UTP nick-end labeling-positive nuclei can be detected predominantly in the secretory coils and rarely in the transitional portions between ducts and end pieces. We suppose that proliferating cells migrate from the ducts to the secretory coils. The secretory product of the eccrine cutaneous glands seems to improve the traction between the foot pads of these animals and the steep and smooth rock formations among which they live.
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cutaneous eccrine glands of the foot pads of the rock hyrax procavia capensis Hyracoidea mammalia
Cells Tissues Organs, 2002Co-Authors: Peter Stumpf, Ulrich WelschAbstract:In order to find correlations between skin gland morphology and specific ethological features, the cutaneous glands of the foot pads of Procavia capensis were studied by histologica
Roscoe Stanyon - One of the best experts on this subject based on the ideXlab platform.
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chromosome painting in the manatee supports afrotheria and paenungulata
BMC Evolutionary Biology, 2007Co-Authors: Margaret E Kellogg, Thomas R Dennis, Brian A. Gray, Roberto T Zori, Peter M Mcguire, Sandra Burkett, Gary Stone, Roscoe StanyonAbstract:Background Sirenia (manatees, dugongs and Stellar's sea cow) have no evolutionary relationship with other marine mammals, despite similarities in adaptations and body shape. Recent phylogenomic results place Sirenia in Afrotheria and with elephants and rock hyraxes in Paenungulata. Sirenia and Hyracoidea are the two afrotherian orders as yet unstudied by comparative molecular cytogenetics. Here we report on the chromosome painting of the Florida manatee.
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Chromosome painting in the manatee supports Afrotheria and Paenungulata
BMC Evolutionary Biology, 2007Co-Authors: Margaret E Kellogg, Thomas R Dennis, Brian A. Gray, Roberto T Zori, Peter M Mcguire, Sandra Burkett, Gary Stone, Roscoe StanyonAbstract:Background Sirenia (manatees, dugongs and Stellar's sea cow) have no evolutionary relationship with other marine mammals, despite similarities in adaptations and body shape. Recent phylogenomic results place Sirenia in Afrotheria and with elephants and rock hyraxes in Paenungulata. Sirenia and Hyracoidea are the two afrotherian orders as yet unstudied by comparative molecular cytogenetics. Here we report on the chromosome painting of the Florida manatee. Results The human autosomal and X chromosome paints delimited a total of 44 homologous segments in the manatee genome. The synteny of nine of the 22 human autosomal chromosomes (4, 5, 6, 9, 11, 14, 17, 18 and 20) and the X chromosome were found intact in the manatee. The syntenies of other human chromosomes were disrupted in the manatee genome into two to five segments. The hybridization pattern revealed that 20 (15 unique) associations of human chromosome segments are found in the manatee genome: 1/15, 1/19, 2/3 (twice), 3/7 (twice), 3/13, 3/21, 5/21, 7/16, 8/22, 10/12 (twice), 11/20, 12/22 (three times), 14/15, 16/19 and 18/19. Conclusion There are five derived chromosome traits that strongly link elephants with manatees in Tethytheria and give implicit support to Paenungulata: the associations 2/3, 3/13, 8/22, 18/19 and the loss of the ancestral eutherian 4/8 association. It would be useful to test these conclusions with chromosome painting in hyraxes. The manatee chromosome painting data confirm that the associations 1/19 and 5/21 phylogenetically link afrotherian species and show that Afrotheria is a natural clade. The association 10/12/22 is also ubiquitous in Afrotheria (clade I), present in Laurasiatheria (clade IV), only partially present in Xenarthra (10/12, clade II) and absent in Euarchontoglires (clade III). If Afrotheria is basal to eutherians, this association could be part of the ancestral eutherian karyotype. If afrotherians are not at the root of the eutherian tree, then the 10/12/22 association could be one of a suite of derived associations linking afrotherian taxa.
Norberto P. Giannini - One of the best experts on this subject based on the ideXlab platform.
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Skull Ontogeny of the Hyraxes Procavia capensis and Dendrohyrax arboreus (Procaviidae: Hyracoidea)
Journal of Mammalian Evolution, 2019Co-Authors: S. Rocío Moyano, Guillermo H. Cassini, Norberto P. GianniniAbstract:Extant hyraxes are small, rabbit-sized, herbivorous paenungulates, with a notable feeding mechanism: they crop with the molars instead of the incisors, unlike most modern hoofed mammals. We investigated the postnatal development of the skull, and their functional correlates, in two extant representative forms of hyraxes, the terrestrial grazer Procavia capensis and the arboreal browser Dendrohyrax arboreus. We measured 18 linear variables representing fundamental descriptive and functional aspects of the skull, and estimated allometric equations on the basis of bivariate and multivariate analyses of an ontogenetic series of 32 specimens of P. capensis and 27 specimens of D. arboreus . Results showed that the ontogenetic trajectories of both species are similar in overall shape and size, but differ in localized regions of the skull associated with the masticatory apparatus. Examples include both differences in degree of allometry (upper postcanine row more positively allometric in Procavia ) as well as opposing trends (positive allometry of diastema length in Dendrohyrax versus negative allometry in Procavia ) . In the mandible, the height of mandible and the length of the lower postcanine row showed significant differences. These changes could be associated with the acquisition of contrasting herbivorous specialization along the browsing-grazing gradient as exemplified in hyraxes.