Tubulidentata Research Articles

Morphological evaluation of the orbit, eye tunics, eyelids, and orbital glands in young and adult aardvarks Orycteropus afer, Pallas, 1766 (Tubulidentata: Orycteropodidae): Similarities and differences with representatives of the Afrotheria clade.

The Afrotheria clade includes a large group of extant mammals, and the aardvark (Orycteropus afer) is the only representative of the order Tubulidentata in it. Here, we studied the morphological nature of the orbital region, eye tunics, upper and lower eyelids, superficial gland of the third eyelid, the third eyelid, deep gland of the third eyelid, and lacrimal gland in post-mortem specimens obtained from three captive aardvarks, two young and one adult. The obtained samples were analyzed using macroscopic, histological, and histochemical methods. We observed choroidal tapetum lucidum fibrosum in all specimens, which was typical for aardvarks. The superficial gland of the third eyelid was a compound multilobar tubular branched gland of a mucous nature. The deep gland of the third eyelid produced a serous secretion. The seromucous secretion was typical for the lacrimal gland. We compared the morphological data of the O. afer skull with that from other endemic African mammals in the Afrotheria clade. We found that other authors provided different anatomical names for some bones and foramina located within the orbit. The types and function of eyelid glands, as well as eyeball glands of aardvarks, can primarily be connected with their habitat. Our study may constitute an introduction to the ontogenesis of individual eyeball glands in aardvarks.

Large Mammals Diversity Assessment in Chilalo-Galema National Park, Ethiopia

A study on the assessment of species diversity of large mammals was conducted in Chilalo Galema Mountain in east Arsi administrative zone from February 2019 to September 2019. The aim of this study was to assess large mammalian species diversity and human-wildlife conflict in Chilalo-Galema Mountain National Park. Line transects and observation methods were used to collect data. Twenty six transect lines were laid, varied in length from 1.41km to 4.34km. Transect width ranged from 200m to 400m. In this study both primary and secondary data were used. Direct observation, body parts, vocalization and indirect evidences such as footprints, burrowing and droppings were used to collect data on diversity of large mammals. Observation and direct count of animals were made during 6:00-10:00 a.m. in the morning and 3:00-6:00 p.m. in the late afternoon when most mammals were active. Species diversity of large mammals was calculated using the Shannon-Weaver index of diversity. The evenness of mammalian species was calculated as J=H’/H’max where H’max=ln(s). 28 species that belong to seven Orders (Primates, Artiodactyla, Carnivora, Hyracoidea, Tubulidentata, Rodentia and Lagomorpha) were identified and recorded during the study. Out of the 252 recorded mammals 26 (10.08%) were order primates, 50 (19.38%) were order carnivora, 1 (0.39%) were order hyracoidea, 6 (2.33%) were order tubulidentata, 164 (63.57%) were artiodactyla, 8 (3.10%) were rodentia and 2 (0.78%) were lagomorpha. Mammalian fauna of the Chilalo Galema Mountain was dominated by two groups of orders, the most abundant orders; namely, order artiodactyla and order carnivora, which contain 164 (63.57%) and 50 (19.38%) mammals respectively. The least abundant was order hyracoidean with 1 (0.39%) recorded mammal. So, Chilalo-Galema is rich in mammalian species diversity and needs conservation measures.

Sex determining region Y (SRY) sequencing and non-invasive molecular sexing in three wild species: brown (Parahyaena brunnea) and spotted (Crocuta crocuta) hyenas and aardvark (Orycteropus afer).

Non-invasive molecular sexing methods are useful in captive breeding programs and field studies; these methods enable sex identification without immobilisation or stressful handling of animals. We developed a method enabling fast and reliable sex identification in three species with limited external sexual dimorphism: the brown and spotted hyenas and the aardvark. We used the sex determining region Y (SRY ) gene as the male-specific sequence and the c-myc gene, highly conserved among mammals, as the control sequence present in both sexes. Primers designed on the basis of the feline and human SRY gene enabled us to amplify and sequence the SRY gene fragment in hyenas and the aardvark. Subsequently, we used specific primers designed on the basis of the newly obtained sequences for sex determination in two brown hyenas, three spotted hyenas and six aardvarks. The sequences of the SRY gene fragments were further studied. Interspecies comparisons revealed high similarity in SRY sequences between both hyena species, as well as their relationships with the Felidae lineage. The aardvark, as the only species of the order Tubulidentata (Afrotheria), showed SRY gene similarities with Sirenia and Primates. Knowledge of phylogenetic relationships can be beneficial in genetic studies focused on species with limited sequence data.

The flexor digitorum breves manus and contrahentes muscles in Afrotheria and other mammals

The mammalian clade Afrotheria was created as a result of Stanhope et al, 1998. Paleontologists and comparative anatomists have struggled to find unique skeletal and dental features that characterize the clade, but there has been very little research on the soft tissue anatomy of afrotherian mammals. My dissertation research has focused on dissecting the forelimbs of members of Afrotheria: three sengis (Order Macroscelidea), two hyraxes (Order Hyracoidea), one aardvark (Order Tubulidentata), two tenrecs and one golden mole (Order Afrosoricida), and comparing their anatomy with published descriptions of other mammals. Features of particular interest within the afrotherian hand are the robust and unusual flexor breves digitorum manus and the pattern of the contrahentes. Also of note are the sesamoid bones in the flexor retinaculum and over the carpals, the relative unimportance of the flexor digitorum superficialis, and the distribution of the median and ulnar nerves.Grant Funding Source: none

A Molecular Phylogeny of Plesiorycteropus Reassigns the Extinct Mammalian Order ‘Bibymalagasia’

Madagascar is well known for its diverse fauna and flora, being home to many species not found anywhere else in the world. However, its biodiversity in the recent past included a range of extinct enigmatic fauna, such as elephant birds, giant lemurs and dwarfed hippopotami. The ‘Malagasy aardvark’ (Plesiorycteropus) has remained one of Madagascar’s least well-understood extinct species since its discovery in the 19th century. Initially considered a close relative of the aardvark (Orycteropus) within the order Tubulidentata, more recent morphological analyses challenged this placement on the grounds that the identifiably derived traits supporting this allocation were adaptations to digging rather than shared ancestry. Because the skeletal evidence showed many morphological traits diagnostic of different eutherian mammal orders, they could not be used to resolve its closest relatives. As a result, the genus was tentatively assigned its own taxonomic order ‘Bibymalagasia’, yet how this order relates to other eutherian mammal orders remains unclear despite numerous morphological investigations. This research presents the first known molecular sequence data for Plesiorycteropus, obtained from the bone protein collagen (I), which places the ‘Malagasy aardvark’ as more closely related to tenrecs than aardvarks. More specifically, Plesiorycteropus was recovered within the order Tenrecoidea (golden moles and tenrecs) within Afrotheria, suggesting that the taxonomic order ‘Bibymalagasia’ is obsolete. This research highlights the potential for collagen sequencing in investigating the phylogeny of extinct species as a viable alternative to ancient DNA (aDNA) sequencing, particularly in cases where aDNA cannot be recovered.

Forelimb anatomy of the aardvark, Orycteropus afer (Mammalia, Tubulidentata)

Soft tissue anatomy, especially myology, has been largely neglected by systematic biologists reconstructing the phylogeny of Mammalia. This is due to inadequate description and illustration of structures in many mammalian orders, and conflicting or inaccurate terminology in the existing descriptions. While anatomical terminology has been standardized for the domestic animals and their myology is well known, many rare mammals have not been dissected in decades and the available descriptions lack standardization and often compare taxa now known to be genetically unrelated. This leaves systematic biologists unable to verify muscle character states in the exotic mammals whose evolutionary relationships are most controversial. For example, little morphological evidence has been found to support the clade Afrotheria, which unites several mammalian orders thought to be unrelated until the advent of genetic sequencing.Here I present the forelimb anatomy of the aardvark, Orycteropus afer, the one living member of the order Tubulidentata and a member of the clade Afrotheria, based on my dissections of two alcohol‐preserved museum specimens. These dissections are part of a dissertation project to document the limb anatomy of several mammalian orders, particularly the little known smaller afrotheres, for use in systematics research. This research was supported by the Field Museum of Natural History Visiting Scholar Fund.Grant Funding SourceNational Science Foundation

Phylogeny and systematics of the Orycteropodidae (Mammalia, Tubulidentata)

The systematics of the order Tubulidentata is poorly known. Its phylogeny has never been thoroughly analysed and only a single review has ever been performed, which was over 30 years ago. This situation has hampered palaeoecological and palaeobiogeographical studies of these Neogene mammals. The present revision of the Orycteropodidae deals with the phylogeny and systematics of all African and Eurasian species over the last 20 Myr. The first comprehensive cladistic analysis of the family is presented here. The results of this analysis, based on 39 coded morphological characters, supplemented by non-coded features taken from all over the skeleton, was used to reconstruct the phylogeny of the order Tubulidentata. Two distinct lineages within the genus Orycteropus are recognized and characterized. The new genus Amphiorycteropus is subsequently created, in order to harmonize taxonomy and phylogeny. The fossil genera Leptorycteropus and Myorycteropus are validated, bringing the number of genera in the order Tubulidentata to four. Moreover, within the family Orycteropodidae, the number of confirmed species is now 14. The outcome of this study allows us to propose a consistent palaeobiogeographical scenario for aardvarks. Finally, this revision represents the most comprehensive work on the evolutionary history of the order Tubulidentata to date, and provides a new framework for future studies. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155, 649–702.

A fossil aardvark (Mammalia, Tubulidentata) from the lower Pliocene of Chad

The Mission Paléoanthropologique Franco-Tchadienne (MPFT) found a new species of Orycteropodidae (Mammalia, Tubulidentata) in the Kollé fossiliferous sector, northern Chad. After Orycteropus abundulafus [Journal of Vertebrate Paleontology 20 (1) (2000) 205–209; Lehmann, T., Vignaud, P., Likius A., Brunet M., in press. A new Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of Northern Chad. Zool. J. Linnean Soc.], this specimen is the second complete skeleton of fossil aardvark found in the Djurab desert. It is the first complete representative of an Orycteropus species found in the Pliocene of Africa. In regard to the Miocene fossil aardvarks, this new taxon, Orycteropus djourabensis nov. sp., shows more affinities with the extant O. afer. The main differences are the larger teeth and the shorter hand in the fossil form. Kossom Bougoudi and Kollé represent a chronological series that gives a unique opportunity for studying the evolution of the African Tubulidentata around the Mio-Pliocene boundary (5.5-4 My). The new species is distinct from the older Chadian Orycteropodid from KB and it embodies the taxonomic turnover that took place within the order Tubulidentata around this boundary in Africa. Moreover, this new species is the oldest known Orycteropus species that clearly belongs to the modern forms including the extant aardvark.

Phylogenetic position of the Tenrecs (Mammalia: Tenrecidae) of Madagascar based on analysis of the complete mitochondrial genome sequence of Echinops telfairi

The phylogenetic position of the lesser hedgehog tenrec, Echinops telfairi, was studied on the basis of analysis of the concatenated sequences of 12 mitochondrial protein‐coding genes. In addition to the tenrec, the analysis included two other representatives of the insectivore order Lipotyphla, the hedgehog and the mole. The eutherian tree was rooted with three non‐eutherian mammalian taxa. The analysis joined the tenrec, the African elephant (order Proboscidea) and the aardvark (order Tubulidentata) on a common branch. The three lipotyphlan taxa, the tenrec (Tenrecidae), the mole (Talpidae) and the hedgehog (Erinaceidae) were dispersed in the eutherian tree, demonstrating lipotyphlan polyphyly.

Cephalic evidence for the affinities of Tubulidentata

Les relations phyletiques de l'ordre des tubulidentes avec les autres ordres de mammiferes sont etudiees d'apres les caracteristiques osseuses, vasculaires et nerveuses de la tete. D'apres certains caracteres les tubulidentes ne seraient pas derives de Condylarthus ou d'autres ongules comme cela est generalement admis

The chromosome complement of the aardvark, Orycteropus afer

The chromosome complement of the aardvark, Oryeteropus afer, consists of 18 metacentric and submetacentric autosomes, a small metacentric X and a little acrocentric Y element. The aardvark is the only member of the Order Tubulidentata. Its relationship to any other taxa is not known, and its karyotype is unique and does not suggest any particular relationship. The DNA content of the nucleus is 1.67 x that of human lymphocytes, a fact not readily explicable by contemporary knowledge of phylogenetic relationships, but similar to the situation found in many Marsupialia. The findings are discussed with regard to evolutionary processes and the phylogenetic position of this species.