Microgale macpheei

Last updated

Microgale macpheei
Temporal range: Holocene
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Afrosoricida
Suborder: Tenrecomorpha
Family: Tenrecidae
Genus: Microgale
Species:
M. macpheei
Binomial name
Microgale macpheei
Goodman, Vasey, and Burney, 2007
Microgale macpheei range.svg
Location of Andrahomana Cave, the only place where Microgale macpheei has been found

Microgale macpheei is an extinct shrew tenrec from southeastern Madagascar. It is known only from two partial skulls found in Andrahomana cave, which radiocarbon dating of associated rodent remains suggests are about 3000 years old. It is the only known recently extinct tenrec. First described in 2007, it is most similar to the smaller Microgale brevicaudata of northern and western Madagascar. M. macpheei has a broad rostrum (front part of the skull) and, like M. brevicaudata, lacks a diastema (gap) between the premolars. A number of details of tooth morphology are characteristic of M. macpheei.

Contents

Taxonomy

Remains of shrew tenrecs (Microgale) were found during expeditions to the cave of Andrahomana in southeastern Madagascar, led by David Burney in 2000 and 2003. [1] The Microgale material was described as a new species, M. macpheei, in 2007 by Steven Goodman, Natalie Vasey, and Burney. [2] The species was named after Ross MacPhee in honor of his contributions to knowledge of the genus Microgale and the paleontology of Madagascar. [3] Goodman and colleagues considered the living Microgale brevicaudata from northern and western Madagascar to be the closest relative of M. macpheei; [4] some populations of this tenrec have since been separated into a different species, M. grandidieri . [5] The common name "MacPhee's shrew tenrec" has been proposed for M. macpheei. [6] The genus of M. macpheei, Microgale, includes more than 20 species and is the largest of the tenrec family, which includes a variety of other Malagasy mammals. [5]

Description

Microgale macpheei is known from two specimens: a damaged cranium (skull without mandibles, or lower jaws) lacking the back part (the parietal bones and further back) as well as the incisors, canines, and second premolars; [Note 1] [2] and another damaged cranium lacking the same parts as well as the left toothrow. [3] Both show no evidence of ongoing tooth replacement, indicating that the permanent dentition is complete. [8] M. macpheei was larger in most measurements than M. brevicaudata, [Note 2] but because of small samples, some differences are not statistically significant. [4] The length of the bony palate in the two specimens of M. macpheei is 9.4 and 9.7 mm, compared to 7.1 to 9.0 mm in eight adult M. brevicaudata. In both specimens, the length of the molar row is 3.0 mm, compared to 2.4 to 2.8 mm in the sample of M. brevicaudata. [10]

The rostrum (front part of the skull) is short and blunt in both M. macpheei and M. brevicaudata, contrasting with the condition in other Microgale, [2] but the rostrum of M. brevicaudata is distinctly more tapered at the front, whereas that of M. macpheei is more blunt at the front. [3] Unlike other Microgale, M. brevicaudata and M. macpheei lack gaps (diastemata) between the premolars. [8] M. macpheei had larger, more robust teeth than M. brevicaudata. [3] In both species, the mesiostyle and distostyle, two crests, on the fourth premolar (P4) and the molars are reduced relative to the condition in other Microgale. [2] M. macpheei lacks an extension of the protocone cusp on the lingual (inner) side of the third upper premolar (P3) and P4, present in M. brevicaudata, and has the paracone cusp on P4 less well-developed. On the other hand, the front part of the ectostyle crest on P4 is larger. The relative lengths of some of the crests on the two last molars [Note 3] also differ between the two species. [3]

Distribution and ecology

Microgale macpheei is known only from the cave of Andrahomana. [3] Its past presence there, like that of the extinct rodent Hypogeomys australis , suggests formerly more mesic (wet) conditions around the cave, which is currently in a dry area. [13] In addition to M. macpheei, three other tenrecs have been described from subfossil material, but none are currently recognized as valid species; [4] thus, M. macpheei is at present the only known recently extinct tenrec species. [13] However, there is a remnant patch of mesic forest near Andrahomana, where a population of M. macpheei may survive. Although no radiocarbon dating has been carried out on M. macpheei remains, bones of the rodent Macrotarsomys petteri from layers in the same cave deposit bracketing those where M. macpheei was found yield dates of around 2480 and 1760 Before Present. [13]

Notes

  1. The dental formula in Microgale is 3.1.3.33.1.3.3 (three incisors, one canine, three premolars, and three molars in both the upper and lower dentition). The three premolars are numbered 2, 3, and 4, as the first premolar is presumed to have been lost. [7]
  2. This description is based on Goodman et al. (2007), published before M. grandidieri and M. brevicaudata were described as distinct species. Much of the material of "M. brevicaudata" used in the 2007 paper is in fact M. grandidieri. [9]
  3. Goodman et al. (2007) are inconsistent in identifying the three molars as M1 through M3 [4] or M2 through M4; [11] the former convention is used in MacPhee's 1987 revision of the genus. [12]

Related Research Articles

<span class="mw-page-title-main">Afrosoricida</span> Order of mammals

The clade Afrosoricida contains the golden moles of Southern Africa, the otter shrews of equatorial Africa and the tenrecs of Madagascar. These three groups of small mammals were for most of the 19th and 20th centuries regarded as a part of the Insectivora or Lipotyphla, but both of those groups, as traditionally used, are polyphyletic.

<span class="mw-page-title-main">Tenrec</span> Family of small mammals

A tenrec is a mammal belonging to any species within the afrotherian family Tenrecidae, which is endemic to Madagascar. Tenrecs are a very diverse group; as a result of convergent evolution, some resemble hedgehogs, shrews, opossums, rats, and mice. They occupy aquatic, arboreal, terrestrial, and fossorial environments. Some of these species, including the greater hedgehog tenrec, can be found in the Madagascar dry deciduous forests. However, the speciation rate in this group has been higher in humid forests.

<i>Plesiorycteropus</i> An extinct genus of eutherian mammals from Madagascar

Plesiorycteropus, also known as the bibymalagasy or Malagasy aardvark, is a recently extinct genus of mammals from Madagascar. Upon its description in 1895, it was classified with the aardvark, but more recent molecular evidence instead suggests that it is most closely related to the tenrecs. Two species are currently recognized, the larger P. madagascariensis and the smaller P. germainepetterae. They probably overlapped in distribution, as subfossil remains of both species have been found in the same site.

<i>Archaeoindris</i> Extinct giant lemur

Archaeoindris fontoynontii is an extinct giant lemur and the largest primate known to have evolved on Madagascar, comparable in size to a male gorilla. It belonged to a family of extinct lemurs known as "sloth lemurs" (Palaeopropithecidae) and, because of its extremely large size, it has been compared to the ground sloths that once roamed North and South America. It was most closely related to Palaeopropithecus, the second largest type of sloth lemur. Along with the other sloth lemurs, Archaeoindris was related to the living indri, sifakas, and woolly lemurs, as well as the recently extinct monkey lemurs (Archaeolemuridae). The genus, Archaeoindris, translates to "ancient indri-like lemur", even though it probably became extinct recently, around 350 BCE.

<span class="mw-page-title-main">Web-footed tenrec</span> Species of mammal

The web-footed tenrec, Malagasy otter shrew, or aquatic tenrec is the only known semiaquatic tenrec, and is found in eastern Madagascar, especially in and around Ranomafana National Park. It grows to between 25 and 39 cm, and was once thought to be extinct. It feeds on crabs, aquatic insects, and crayfish. The population is considered vulnerable. It was formerly placed in the monotypic genus Limnogale, but has been moved to Microgale based on molecular data showing it to be deeply nested within the latter.

<span class="mw-page-title-main">Short-tailed shrew tenrec</span> Species of mammal

The short-tailed shrew tenrec is a species of mammal in the family Tenrecidae. It is endemic to Madagascar. Its natural habitats are subtropical and tropical dry and moist lowland forests.

<i>Microgale</i> Genus of mammals

Microgale is a genus of mammal in the family Tenrecidae. There are 21 living species on the island of Madagascar and one extinct species known from a fossil. Some species have been discovered in the last twenty years.

<span class="mw-page-title-main">Jenkins's shrew tenrec</span> Species of mammal

Jenkins's shrew tenrec is a species of mammal in the family Tenrecidae. It is endemic to Madagascar. Its natural habitats are subtropical or tropical dry forests and shrubland. It is threatened by habitat loss.

<span class="mw-page-title-main">Greater long-tailed shrew tenrec</span> Species of mammal

The greater long-tailed shrew tenrec is a species of mammal in the family Tenrecidae. It is endemic to Madagascar, where its natural habitats are subtropical or tropical moist forests.

<span class="mw-page-title-main">Talazac's shrew tenrec</span> Species of mammal

Talazac's shrew tenrec is a species of mammal in the family Tenrecidae. It is endemic to Madagascar. Its natural habitats are subtropical or tropical moist forests. On the basis of molecular data indicating that it and Dobson's shrew tenrec form a sister group to the rest of Microgale, these two species were transferred from Microgale to Nesogale in 2016.

<i>Hypogeomys australis</i> An extinct rodent from central and southeastern Madagascar

Hypogeomys australis is an extinct rodent from central and southeastern Madagascar. First described in 1903, it is larger than its close relative, the living Hypogeomys antimena, which occurs further west, but otherwise similar. Average length of the femur is 72.1 mm, compared to 63.8 mm in H. antimena. One of the few extinct rodents of Madagascar, it survived to at least around 1536 BP based on radiocarbon dating. Little is known of its ecology, but it may have lived in burrows like its living relative and eaten some arid-adapted plants.

<span class="mw-page-title-main">Central Highlands (Madagascar)</span> Biogeographical region in Central Madagascar

The Central Highlands, Central High Plateau, or Hauts-Plateaux are a mountainous biogeographical region in central Madagascar. They include the contiguous part of the island's interior above 800 m (2,600 ft) elevation. The Central Highlands are separated from the Northern Highlands of the northern tip of Madagascar by a low-lying valley, the Mandritsara Window, which has apparently acted as a barrier to dispersal for species in the highlands, leading to species pairs such as Voalavo gymnocaudus and Voalavo antsahabensis in the Northern and Central Highlands. Species restricted to the Central Highlands include the bats Miniopterus manavi and Miniopterus sororculus; the rodents Brachyuromys betsileoensis and Voalavo antsahabensis; the tenrecs Hemicentetes nigriceps and Oryzorictes tetradactylus; and the lemur Cheirogaleus sibreei. Because of the continuous habitat of the Central Highlands, there is little local endemism, unlike the Northern Highlands.

<span class="mw-page-title-main">Malagasy mountain mouse</span> Small rodent found in the highlands of eastern Madagascar

The Malagasy mountain mouse or Koopman's montane voalavo is a rodent within the subfamily Nesomyinae of the family Nesomyidae. It is monotypic within the genus Monticolomys, and is closely related to the big-footed mouse (Macrotarsomys). It is found in the highlands of eastern Madagascar. A small mouse-like rodent, it is dark brown on the upperparts and dark gray below. It has small, rounded, densely haired ears and broad feet with well-developed pads. The long tail lacks a tuft at the tip. The skull is delicate and lacks crests and ridges on its roof.

<span class="mw-page-title-main">Petter's big-footed mouse</span> Species of Madagascan rodent

Petter's big-footed mouse, is a Madagascan rodent in the genus Macrotarsomys. With a head and body length of 150 mm (5.9 in) and body mass of 105 g (3.7 oz), it is the largest species of its genus. Its upper body is brown, darkest in the middle of the back, and the lower body is white to yellowish. The animal has long whiskers, short forelimbs, and long hindfeet. The tail ends in a prominent tuft of long, light hairs. The skull is robust and the molars are low-crowned and cuspidate.

<i>Microgale grandidieri</i> Species of mammal

Microgale grandidieri, also known as Grandidier's shrew tenrec, is a species of shrew tenrec occurring in the dry forests of western and southwestern Madagascar. Populations of this species were formerly included in Microgale brevicaudata; M. grandidieri was described as a separate species in 2009 based on differences in morphology and DNA sequences.

<span class="mw-page-title-main">Oryzorictinae</span> Subfamily of mammals

Oryzorictinae is a subfamily of tenrecs endemic to the island of Madagascar. It is the largest of three tenrec subfamilies. Oryzorictinae is thought to have split from the lineage of its closest relative, Geogale, about 30 million years (Ma) ago. The deepest phylogenetic split within the subfamily, that between Oryzorictes and a clade composed of Microgale plus Nesogale, is thought to have occurred about 28 Ma ago. In turn, Microgale and Nesogale are thought to have diverged about 19 Ma ago.

<i>Nesogale</i> Genus of mammals

Nesogale is a genus of tenrecs, which are a family of afrotherian mammals endemic to Madagascar. On the basis of molecular data indicating its two species form a sister group to the rest of Microgale, they were transferred from Microgale to Nesogale in 2016, thus resurrecting a genus first erected by Oldfield Thomas in 1918. These genera, along with Oryzorictes, form the tenrec subfamily Oryzorictinae. Nesogale contains the following species:

Ampasambazimba is a mountain peak and subfossil site in Madagascar, near Analavory, (Itasy) most known for being the site of the remains of the extinct giant sloth lemur Archaeoindris.

References

  1. Goodman et al., 2007, p. 368
  2. 1 2 3 4 Goodman et al., 2007, p. 370
  3. 1 2 3 4 5 6 Goodman et al., 2007, p. 371
  4. 1 2 3 4 Goodman et al., 2007, p. 373
  5. 1 2 Olson et al., 2009, p. 1095
  6. Muldoon et al., 2009, p. 1117
  7. MacPhee, 1987, p. 11
  8. 1 2 Goodman et al., 2007, pp. 370–371
  9. Olson et al., 2009, p. 1107
  10. Goodman et al., 2007, table 1
  11. Goodman et al., 2007, pp. 369–370
  12. E.g., MacPhee, 1987, fig. 8
  13. 1 2 3 Goodman et al., 2007, p. 374

Literature cited