The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Francesco Rovero - One of the best experts on this subject based on the ideXlab platform.
-
Evolutionary History of the Grey-Faced Sengi, Rhynchocyon udzungwensis, from Tanzania: A Molecular and Species Distribution Modelling Approach
2016Co-Authors: Lucinda P. Lawson, Cristiano Vernesi, Silvia Ricci, Francesco RoveroAbstract:Rhynchocyon udzungwensis is a recently described and poorly understood sengi (giant Elephant-Shrew) endemic to two small montane forests in Southern Tanzania, and surrounded in lower forests by R. cirnei reichardi. In this study, we investigate the molecular genetic relationship between R. udzungwensis and R. c. reichardi, and the possible role that shifting species distributions in response to climate fluctuations may have played in shaping their evolutionary history. Rhynchocyon udzungwensis and R. c. reichardi individuals were sampled from five localities for genetic analyses. Three mitochondrial and two nuclear loci were used to construct species trees for delimitation and to determine whether introgression was detectable either from ancient or ongoing hybridization. All species-tree results show R. udzungwensis and R. c. reichardi as distinct lineages, though mtDNA shows evidence of introgression in some populations. Nuclear loci of each species were monophyletic, implying introgression is exclusively historical. Because we found evidence of introgression, we used distribution data and species distribution modelling for present, glacial, and interglacial climate cycles to predict how shifting species distributions may have facilitated hybridization in some populations. Though interpretations are affected by the limited range of these species, a likely scenario is that the mtDNA introgression found in eastern mid-elevation populations was facilitated by low numbers of R. udzungwensis that expanded into lowland heavily occupied R. c. reichardi areas during interglacial climate cycles. These results imply that relationships within the genus Rhynchocyon may b
-
Brain Volume of the Newly-Discovered Species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): Implications for Encephalization in
2016Co-Authors: Jason A. Kaufman, Gregory H. Turner, Patricia A. Holroyd, Francesco Rovero, Ari GrossmanAbstract:The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (Elephant-Shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-relate
-
Brain volume of the newly-discovered species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): implications for encephalization in sengis.
PloS one, 2013Co-Authors: Jason A. Kaufman, Gregory H. Turner, Patricia A. Holroyd, Francesco Rovero, Ari GrossmanAbstract:The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (Elephant-Shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-related insectivorous afrotheres, or with more-distantly-related insectivorous laurasiatheres.
-
a new species of giant sengi or Elephant Shrew genus rhynchocyon highlights the exceptional biodiversity of the udzungwa mountains of tanzania
Journal of Zoology, 2008Co-Authors: Francesco Rovero, Galen B. Rathbun, Andrew Perkin, Trevor Jones, David O Ribble, C Leonard, R R Mwakisoma, Nike DoggartAbstract:A new species of sengi, or Elephant-Shrew, is described. It was discovered in the northern Udzungwa Mountains of Tanzania in 2005. Sengis (Order Macroscelidea, super-cohort Afrotheria) include four genera and 15 species of mammals that are endemic to Africa. This discovery is a significant contribution to the systematics of this small order. Based on 49 camera trap images, 40 sightings and five voucher specimens, the new sengi is diurnal and distinguished from the other three species of Rhynchocyon by a grizzled grey face, pale yellow to cream chest and chin, orange-rufous sides, maroon back and jet-black lower rump and thighs. The body weight of the new species is about 700 g, which is 25–50% greater than any other giant sengi. The new Rhynchocyon is only known from two populations that cover about 300 km2 of montane forest. It has an estimated density of 50–80 individuals km−2. This discovery has important implications for the conservation of the high biodiversity that is found in the forests of the Eastern Arc Mountains.
-
A new species of giant sengi or Elephant‐Shrew (genus Rhynchocyon) highlights the exceptional biodiversity of the Udzungwa Mountains of Tanzania
Journal of Zoology, 2008Co-Authors: Francesco Rovero, Galen B. Rathbun, Andrew Perkin, Trevor Jones, David O Ribble, C Leonard, R R Mwakisoma, Nike DoggartAbstract:A new species of sengi, or Elephant-Shrew, is described. It was discovered in the northern Udzungwa Mountains of Tanzania in 2005. Sengis (Order Macroscelidea, super-cohort Afrotheria) include four genera and 15 species of mammals that are endemic to Africa. This discovery is a significant contribution to the systematics of this small order. Based on 49 camera trap images, 40 sightings and five voucher specimens, the new sengi is diurnal and distinguished from the other three species of Rhynchocyon by a grizzled grey face, pale yellow to cream chest and chin, orange-rufous sides, maroon back and jet-black lower rump and thighs. The body weight of the new species is about 700 g, which is 25–50% greater than any other giant sengi. The new Rhynchocyon is only known from two populations that cover about 300 km2 of montane forest. It has an estimated density of 50–80 individuals km−2. This discovery has important implications for the conservation of the high biodiversity that is found in the forests of the Eastern Arc Mountains.
Clare D. Fitzgibbon - One of the best experts on this subject based on the ideXlab platform.
-
comparative ecology of two Elephant Shrew species in a kenyan coastal forest
Mammal Review, 1995Co-Authors: Clare D. FitzgibbonAbstract:The Four-toed Elephant-Shrew Petrodromus tetradactylus is one of the most widely distributed Elephant-Shrew species, ranging from Kenya to South Africa, while the Golden-rumped Elephant Shrew Rhynchocyon chrysopygus has a limited distribution, being found only on the north Kenya coast. This paper compares the behaviour and ecology of the two species in Arabukc-Sokoke Forest, Kenya. Compared with Four-toed Elephant-Shrews, Golden-rumped Elephant-Shrews have larger home ranges and maintain lower densities, as predicted from their greater body size. Both species prefer areas with dense vegetation cover, avoiding open areas, but the Four-toed ElephantShrew shows a greater preference for dense thicket areas. Territory size was inversely correlated with dry-season spider abundance in Golden-rumped Elephant-Shrews, and with dry-season ant abundance in Four-toed Elephant-Shrews. Differences in activity patterns, as well as body size, may contribute to niche separation between the two species. Both species appear to be monogamous, with males and females defending overlapping territories. Male Golden-rumped Elephant-Shrews range over slightly larger areas than females, and are more likely to trespass into neighbouring territories. The less specific habitat requirements of Four-toed Elephant-Shrews and their higher densities are probably the two most important factors resulting in their wide distributional range.
-
Ultrastructure of Spermatozoa of the Yellow-rumped Elephant Shrew Rhynchocyon chrysopygus (Mammalia: Macroscelidea) and the Phylogeny of Elephant Shrews
Acta Zoologica, 1995Co-Authors: Peter F Woodall, Clare D. FitzgibbonAbstract:The spermatozoa of the yellow‐rumped Elephant Shrew Rhynchocyon chrysopygus have a spatulate head, tapering to a rounded proximal end with a marked narrowing at the equatorial segment. There is a short pointed subacrosome and about 24 gyres of mitochondria were found in the midpiece. The coarse fibres surrounding the axonome show enlargement of numbers 1, 5, 6 and 9. The spermatozoa of all genera of Elephant Shrews have now been described allowing comparisons among them. R. chrysopygus has the shortest spermatozoon and the fewest number of gyres. The pointed subacrosome is considered an ancestral feature and is shared with Macroscelides. The enlargement of coarse fibres 1, 5, 6 and 9 is found in several groups including members of the archonta and paenungulates, both postulated as being related to Elephant Shrews. 1995 The Royal Swedish Academy of Sciences
-
Comparative ecology of two Elephant‐Shrew species in a Kenyan coastal forest
Mammal Review, 1995Co-Authors: Clare D. FitzgibbonAbstract:The Four-toed Elephant-Shrew Petrodromus tetradactylus is one of the most widely distributed Elephant-Shrew species, ranging from Kenya to South Africa, while the Golden-rumped Elephant Shrew Rhynchocyon chrysopygus has a limited distribution, being found only on the north Kenya coast. This paper compares the behaviour and ecology of the two species in Arabukc-Sokoke Forest, Kenya. Compared with Four-toed Elephant-Shrews, Golden-rumped Elephant-Shrews have larger home ranges and maintain lower densities, as predicted from their greater body size. Both species prefer areas with dense vegetation cover, avoiding open areas, but the Four-toed ElephantShrew shows a greater preference for dense thicket areas. Territory size was inversely correlated with dry-season spider abundance in Golden-rumped Elephant-Shrews, and with dry-season ant abundance in Four-toed Elephant-Shrews. Differences in activity patterns, as well as body size, may contribute to niche separation between the two species. Both species appear to be monogamous, with males and females defending overlapping territories. Male Golden-rumped Elephant-Shrews range over slightly larger areas than females, and are more likely to trespass into neighbouring territories. The less specific habitat requirements of Four-toed Elephant-Shrews and their higher densities are probably the two most important factors resulting in their wide distributional range.
-
The distribution and abundance of the golden-rumped Elephant-Shrew Rhynchocyon chrysopygus in Kenyan coastal forests
Biological Conservation, 1994Co-Authors: Clare D. FitzgibbonAbstract:Abstract The most important site for the golden-rumped Elephant-Shrew Rhynchocyon chrysopygus is Arabuko-Sokoke Forest, providing 372 km 2 of protected habitat supporting over 20 000 individuals. While this species continues to occur in a number of other forest patches on the north Kenya coast, these are all very small (total area 27 km 2 ) and their continued existence is in doubt. The Elephant-Shrew is not restricted to true forest, also occurring in some scrub and degraded woodland habitats (covering less than 500 km 2 ), although usually at low densities. Boni Forest, north of Tana River, and small forest patches nearby, may provide additional habitat, but there is currently no information on the status of the golden-rumped Elephant-Shrew in this area. At the levels recorded in Arabuko-Sokoke, trapping and habitat modification resulting from pole cutting and selective tree felling, have little effect on Elephant-Shrew densities but high levels of both these factors probably account for the low densities recorded outside protected areas. While current evidence suggests that the species is not in immediate danger, the maintenance of Arabuko-Sokoke Forest is essential for its continued existence. Its present conservation status is considered to be threatened, on account of its restricted range, small isolated populations, and rapid loss of habitat.
-
Surveying Rhynchocyon Elephant‐Shrews in tropical forest
African Journal of Ecology, 1994Co-Authors: Clare D. Fitzgibbon, Galen B. RathbunAbstract:Summary A survey for Rhynchocyon Elephant-Shrews, based on the abundance of nests along strip transects, was developed and calibrated using data from a detailed study of the ecology of the Golden-rumped Elephant-Shrew Rhynchocyon chrysopygus. Using this method, the density of Golden-rumped Elephant-Shrews in three different habitats within Arabuko-Sokoke Forest, Kenya was determined, and was found to range from 23 to 75 animals per square kilometre. Resume On a realise une etude des rats a trompe (Rhinchocyori) basee sur l'abondance de nids le long de bandes transects et on l'a calibree en se servant de donnees provenant d'une etude detaillee de l'ecologie du rat a trompe a croupe doree, Rhynchocyon chrysopygus. Grâce e cette methode, on a determine la densite de cette musaraigne dans trois habitats differents de la foret Arabuko-Sokoke, au Kenya, et elle est evaluee entre 23 et 75 animaux par km2.
Ari Grossman - One of the best experts on this subject based on the ideXlab platform.
-
Brain Volume of the Newly-Discovered Species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): Implications for Encephalization in
2016Co-Authors: Jason A. Kaufman, Gregory H. Turner, Patricia A. Holroyd, Francesco Rovero, Ari GrossmanAbstract:The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (Elephant-Shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-relate
-
Brain volume of the newly-discovered species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): implications for encephalization in sengis.
PloS one, 2013Co-Authors: Jason A. Kaufman, Gregory H. Turner, Patricia A. Holroyd, Francesco Rovero, Ari GrossmanAbstract:The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (Elephant-Shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-related insectivorous afrotheres, or with more-distantly-related insectivorous laurasiatheres.
Nomakwezi Mzilikazi - One of the best experts on this subject based on the ideXlab platform.
-
Seasonal changes in thermogenesis of a free-ranging afrotherian small mammal, the Western rock Elephant Shrew (Elephantulus rupestris).
Journal of comparative physiology. B Biochemical systemic and environmental physiology, 2012Co-Authors: Rebecca Oelkrug, Carola W. Meyer, Gerhard Heldmaier, Nomakwezi MzilikaziAbstract:We report on the seasonal metabolic adjustments of a small-sized member of the phylogenetically ancient Afrotheria, the Western rock Elephant Shrew (Elephantulus rupestris). We recorded body temperature (Tb) patterns and compared the capacity for adrenergically induced nonshivering thermogenesis (NST) in E. rupestris captured in the wild in summer and winter. Noradrenaline (NA) treatment (0.4–0.5 mg/kg, s.c.) induced a pronounced elevation in oxygen consumption compared to controls (saline), and the increase in oxygen consumption following injection of NA was 1.8-fold higher in winter compared to summer. This suggests that the smaller members of Afrotheria possess functional brown adipose tissue, which changes in thermogenic capacity depending on the season. Torpor was recorded in both seasons, but in winter the incidence of torpor was higher (n = 205 out of 448 observations) and minimal Tb during torpor was lower (Tbmin: 11.9°C) than in summer (n = 24 out of 674 observations; Tbmin: 26°C). In addition to cold, high air humidity emerged as a likely predictor for torpor entry. Overall, E. rupestris showed a high degree of thermoregulatory plasticity, which was mainly reflected in a variable timing of torpor entry and arousal. We conclude that E. rupestris exhibits seasonal metabolic adjustments comparable to what has been long known for many Holarctic rodents.
-
Ticks of four-toed Elephant Shrews and Southern African hedgehogs.
The Onderstepoort journal of veterinary research, 2011Co-Authors: Ivan Gerard Horak, Shaun Welman, Stacey L. Hallam, Heike Lutermann, Nomakwezi MzilikaziAbstract:Several studies on ticks infesting small mammals, including Elephant Shrews, have been conducted in South Africa; however, these studies have included only a single four-toed Elephant Shrew and no hedgehogs. This study thus aimed to identify and quantify the ixodid ticks infesting four-toed Elephant Shrews and Southern African hedgehogs. Four-toed Elephant Shrews ( Petrodromus tetradactylus ) were trapped in dense shrub undergrowth in a nature reserve in north-eastern KwaZulu-Natal. They were separately housed, first in cages and later in glass terraria fitted with wire-mesh bases to allow detached ticks to fall through for collection. Southern African hedgehogs ( Atelerix frontalis ) were hand caught on a farm in the eastern region of the Northern Cape Province and all visible ticks were collected by means of tweezers while the animals were anaesthetised. The ticks from each animal were preserved separately in 70% ethanol for later identification and counting. The immature stages of five ixodid tick species were collected from the Elephant Shrews, of which Rhipicephalus muehlensi was the most common. It has not been recorded previously on any species of Elephant Shrew. Three ixodid tick species were collected from the hedgehogs. Large numbers of adult Haemaphysalis colesbergensis , which has not been encountered previously on hedgehogs, were collected from these animals. Four-toed Elephant Shrews are good hosts of the larvae and nymphs of R. muehlensi , and Southern African hedgehogs are good hosts of adult H. colesbergensis .
-
Ticks of four-toed Elephant Shrews and Southern African hedgehogs : original research
Onderstepoort Journal of Veterinary Research, 2011Co-Authors: Ivan Gerard Horak, Nomakwezi Mzilikazi, Shaun Welman, Stacey L. Hallam, Heike LutermannAbstract:Several studies on ticks infesting small mammals, including Elephant Shrews, have been conducted in South Africa; however, these studies have included only a single four-toed Elephant Shrew and no hedgehogs. This study thus aimed to identify and quantify the ixodid ticks infesting four-toed Elephant Shrews and Southern African hedgehogs. Four-toed Elephant Shrews (Petrodromus tetradactylus) were trapped in dense shrub undergrowth in a nature reserve in north-eastern KwaZulu-Natal. They were separately housed, first in cages and later in glass terraria fitted with wire-mesh bases to allow detached ticks to fall through for collection. Southern African hedgehogs (Atelerix frontalis) were hand caught on a farm in the eastern region of the Northern Cape Province and all visible ticks were collected by means of tweezers while the animals were anaesthetised. The ticks from each animal were preserved separately in 70% ethanol for later identification and counting. The immature stages of five ixodid tick species were collected from the Elephant Shrews, of which Rhipicephalus muehlensi was the most common. It has not been recorded previously on any species of Elephant Shrew. Three ixodid tick species were collected from the hedgehogs. Large numbers of adult Haemaphysalis colesbergensis, which has not been encountered previously on hedgehogs, were collected from these animals. Four-toed Elephant Shrews are good hosts of the larvae and nymphs of R. muehlensi, and Southern African hedgehogs are good hosts of adult H. colesbergensis.
-
Noradrenalin induces thermogenesis in a phylogenetically ancient eutherian mammal, the rock Elephant Shrew, Elephantulus myurus
Journal of Comparative Physiology B, 2006Co-Authors: Nomakwezi Mzilikazi, Barry G. LovegroveAbstract:The evolution of endothermy is thought to have been facilitated by the advent of endothermic energy sources such as brown adipose tissue (BAT), the principal site of non-shivering thermogenesis (NST). In marsupials, heat is primarily produced through shivering and NST in skeletal muscle because BAT is either absent or appears to be non-functional. The most basal group of the eutherian lineage are the Afrotheria. Rock Elephant Shrews, Elephantulus myurus are amongst the smallest members of the Afrotheria and are also known to use exogenous passive heating. The aim of this study was to determine whether the reliance on passive heating compromised the capacity for thermogenesis in E. myurus . We measured the thermogenic response to noradrenalin (NA) injection in E. myurus acclimated to short photoperiod. The thermogenic response at 25°C was 1.58 ml O_2 g^−1 h^−1. We used phylogenetically independent analyses to establish how this thermogenic response compared to other eutherians that display classical NST. The thermogenic response of E. myurus was not significantly different from phylogenetically independent allometric predictions. However, it is unclear whether this thermogenic response is indicative of classical NST and molecular data are required to verify the presence of BAT and UCPs in Elephant Shrews.
Patricia A. Holroyd - One of the best experts on this subject based on the ideXlab platform.
-
Brain Volume of the Newly-Discovered Species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): Implications for Encephalization in
2016Co-Authors: Jason A. Kaufman, Gregory H. Turner, Patricia A. Holroyd, Francesco Rovero, Ari GrossmanAbstract:The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (Elephant-Shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-relate
-
Brain volume of the newly-discovered species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): implications for encephalization in sengis.
PloS one, 2013Co-Authors: Jason A. Kaufman, Gregory H. Turner, Patricia A. Holroyd, Francesco Rovero, Ari GrossmanAbstract:The Gray-faced Sengi (Rhynchocyon udzungwensis) is a newly-discovered species of sengi (Elephant-Shrew) and is the largest known extant representative of the order Macroscelidea. The discovery of R. udzungwensis provides an opportunity to investigate the scaling relationship between brain size and body size within Macroscelidea, and to compare this allometry among insectivorous species of Afrotheria and other eutherian insectivores. We performed a spin-echo magnetic resonance imaging (MRI) scan on a preserved adult specimen of R. udzungwensis using a 7-Tesla high-field MR imaging system. The brain was manually segmented and its volume was compiled into a dataset containing previously-published allometric data on 56 other species of insectivore-grade mammals including representatives of Afrotheria, Soricomorpha and Erinaceomorpha. Results of log-linear regression indicate that R. udzungwensis exhibits a brain size that is consistent with the allometric trend described by other members of its order. Inter-specific comparisons indicate that macroscelideans as a group have relatively large brains when compared with similarly-sized terrestrial mammals that also share a similar diet. This high degree of encephalization within sengis remains robust whether sengis are compared with closely-related insectivorous afrotheres, or with more-distantly-related insectivorous laurasiatheres.
-
Early tertiary Elephant-Shrews from Egypt and the origin of the Macroscelidea.
Proceedings of the National Academy of Sciences of the United States of America, 1991Co-Authors: Elwyn L. Simons, Patricia A. Holroyd, Thomas M. BownAbstract:Recent expeditions to the Fayum Depression, Egypt, have made possible the discovery of mandibles and a maxilla of a new genus and species of late Eocene Elephant-Shrew as well as initial evidence of the upper dentition of the early Oligocene taxon Metoldobotes. These fossils demonstrate that macroscelideans underwent a significant radiation in the Early Tertiary of Africa. Two new subfamilies are recognized and described. These Tertiary macroscelideans are the most primitive Elephant-Shrews known and indicate that previous hypotheses of a close phylogenetic relationship between macroscelideans and either lagomorphs, erinaceotans, or tree-Shrews are unlikely. Rather, the dental anatomy of the Fayum macroscelideans provides evidence for a derivation of the order from within the Condylarthra.