A new species of White-tootherd Shrew from Vietnam.

Shrews (Soricidae) are small insectivorous or omnivorous Mammals found across much of the world, the only major landmasses from which they are absent being Australia, New Zealand and New Guinea, though they are restricted to the northwest of South America, suggesting they are recent arrivals in that continent. They are small animals, superficially resembling Mice, though they are not closely related to Rodents, with the largest species reaching only about 15 cm. Shrews are notoriously verocious eaters, consuming around 80-90% of their bodyweight each day. They also reproduce extremely rapidly, with females of many species able to produce up to ten litters of young a year, though they seldom live more than 30 months. The White-toothed Shrews (there are also Red-toothed Shrews) are found across Eurasia and Africa. They are the most diverse group of Shrews, and contain both the largest and smallest species in the group.

In a paper published in the journal ZooKeys on 2 July 2013, Paulina Jenkins of The Natural History Museum in London, Alexei Abramov of the Zoological Institute of the Russian Academy of Sciences and the Joint Vietnam-Russian Tropical Research and Technological Centre, Anna Bannikova of the Lomonosov Moscow State University and Viatcheslav Rozhnov of the A.N. Severtsov Institute of Ecology and Evolution of the  Russian Academy of Sciences and the Joint Vietnam-Russian Tropical Research and Technological Centre, describe a new species of White Toothed Shrew from Vietnam.

The new species is place in the genus Crocidura and given the specific name Crocidura sapaensis, after the Sa Pa District in Lao Cai Province, where it was discovered. Crocidura sapaensis is a small (~100 mm) dark, greyish brown Shrew. It was found living a variety of habitats in the vicinity of Tram Ton Station in Hoang Lien National Park, at altitudes of between 1930 and 2200 m, where it seemed to be locally abundant.

Crocidura sapaensis, adult male. Jenkins et al. (2013).

Typical environment in the area of Hoang Lien National Park where Crocidura sapaensis was found living. Jenkins et al. (2013).

The approximate location of the Hoang Lien National Park. Google Maps.

See also Hunting the lost Opossum, The diet of the Langebaanweg Hyaenids, Signs of scavenging on a Pliocene Argentinean Glyptodont, A 'South American' Marsupial from the early Eocene of Australia and A Eutherian Mammal from the Late Cretaceous of Kazakhstan.

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Small Llamas from the Late Pleistocene of Central Mexico.

 Camelids (Camels and Llamas) originated in North America about 45 million years ago, from where they spread to Eurasia about 6 million years ago and South America about 1.8 million years ago. They became extinct in North America at the end of the Pleistocene, probably as a result of the arival of humans, but persisted in South America and Eurasia, from where they have been introduced to Africa and more recently Australia.

The small Llama Hemiauchenia gracilis is known from a number of  Late Pliocene to Middle Pleistocene sites across North America, from Idaho south to Mexico and east to Florida. In a paper published in the journal Acta Palaeontologica Polonica on 29 June 2012, Victor Bravo−Cuevas of the Museo de Paleontología at the Área Académica de Biología at the Universidad Autónoma del Estado de Hidalgo, Eduardo Jiménez−Hidalgo of the Laboratorio de Paleobiología at the Instituto de Recursos at the Universidad del Mar, and Gloria Cuevas−Ruiz and Miguel A. Cabral−Perdomo, also of the Área Académica de Biología at the Universidad Autónoma del Estado de Hidalgo describe new material assigned to Hemiauchenia gracilis from three Late Pleistocene sites in Hildago State in Central Mexico.

Map showing the sites where the new material referred to Hemiauchenia gracilis was discovered. Bravo-Cuevas et al. (2012).

The new material came from three separate sites in Hildago State, all assigned to the Rancholbrean North American Faunal Stage on the basis of other fossils present, making them between 240 000 and 11 000 years old; this is the last faunal stage of the Pleistocene in North America.

The first site, Barranca del Berrendo, yielded a partial skull and the distal portion of metatarsels III and IV (foot bones).

Partial skull of Hemiauchenia gracilis from Barranca del Berrendo. (A) Cranial vault in dorsal view. (B) Cranial vault in lateral view. (C) Maxillary fragment in dorsal view. (D) Maxillary fragment in ventral view. (E) Maxillary fragment in lateral view. The arrows in E
indicate mesowear patters: high occlusal relief (OR) and sharp cusp shape (CS). Bravo-Cuevas et al. (2012).

Distal portions of metatarsals III and IV of Hemiauchenia gracilis in anterior view. Bravo-Cuevas et al. (2012).

The second site, Barranca San Agustín produced the distal parts of a left scapula (shoulder blade) and left tibia (shinbone).

 

Material referred to Hemiauchenia gracilis from Barranca San Agustín. (A) Distal end of left scapula in lateral view. (B) Distal end of left tibia (UAHMO−515) in anterior (B1) and distal (B2) views, showing the articular surface. Bravo-Cuevas et al. (2012).

The third site, El Barrio, produced a fragmentary left mandible (jawbone), a metatarsal fragment and two proximal phalanges (knuckle bones) of the same individual.

Mandible and lower dentition of the camelid Hemiauchenia gracilis, in lateral (A) and occlusal (B) views. Bravo-Cuevas et al. (2012).

Left metatarsal of the camelid Hemiauchenia gracilis in anterior (A1) and proximal (A2) views,
showing the articular surface. Bravo-Cuevas et al. (2012).

Proximal phalanges of the camelid Hemiauchenia gracilis (A) right in anterior (A1) and posterior (A2) views and (B) left in anterior (B1) and posterior (B2) views. Bravo-Cuevas et al. (2012).

These are the latest known specimens of Hemiauchenia gracilis and are at the southern end of the species known range. This suggests that the species became restricted in the southern part of its range as the Pleistocene progressed, with fossils from the earliest part of its range, the Early Blancan Faunal Stage (equivalent to the Late Pliocene, or between 4.3 and 2.6 million years ago) found from Idaho to Mexico, then by the Late Blancan (Early Pleistocene, or 2 588 000 to 1 808 000 years ago) being found no further north than Arizona, New Mexico and Florida, then in the Irvingtonian (Middle Pleistocene, 1,800,000 to 240,000 years ago) being restricted to Mexico, with the new Rancholabrean fossils found only in Central Mexico.

Map showing the distribution of known sites producing Hemiauchenia gracilis material, with approximate dates  represented by symbols. Bravo-Cuevas et al. (2012).

Like many (most) scientific theories this diminishing distribution over time is only testable in that it could potentially be disproved. A single fossil in an area where the species was thought to have become locally extinct would prove the theory wrong, but it is never possible to say with complete confidence that it was absent from an area, since absence of evidence is not evidence of absence, so the theory can never actually be proved.

See also New species of Ground Opossum from eastern Bolivia, New Caviomorph Rodents from the Early Oligocene Tinguiririca Fauna of the Andean Main Range of central Chile, A new Ground Sloth from the Late Miocene of Argentina, The origin of domestic dogs, and Mammals on Sciency Thoughts YouTube.

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A new species of Nectar-Feeding Bat from Brazil.

New World Nectar-Feeding Bats (Phyllostomidae) evolved separately from the Nectar-Feeding Bats of the Old World (which may themselves represent more than one evolutionary lineage). They can be split into two distinct groups, the Lonchophyllinae which extract nectar by the means of two deep groves on either side of their tongue, and the Glossophaginae, which feed by means of a brush-like apparatus on their tongues. 

In a paper published in the American Museum Novitates on 25 June 2012, Marcelo Nogueira, Isaac Lima and Adriano Peracchi of the Laboratório de Mastozoologia at the Universidade Federal Rural do Rio de Janeiro and Nancy Simmons of the Department of Mammalogy at the Division of Vertebrate Zoology at the American Museum of Natural History describe a new species of Glossophagin Bat from the Coastal Forests of Brazil.

The new species is described from two Bats captured in tableland Atlantic forest at the Reserva Natural Vale in the north of the state of Espírito Santo, in southeastern Brazil, and a third specimen from  semideciduous seasonal tableland Atlantic forest at the Floresta Nacional de Goytacazes reserve about 30 km south on the right bank of the Rio Doce. These tableland forests are considered to be the most botanically species rich parts of the Atlantic Forests.

Map showing the location of the Reserva Natural Vale and Floresta Nacional de Goytacazes reserves. Nogueira et al. (2012).

The new species is named Dryadonycteris capixaba, where Dryadonycteris means 'bat from Dryades' (a reference to the name 'Dryades' which was used by the 19th-century German naturalist Karl Friedrich Philipp von Martius to describe the Atlantic Forrest Floral Province) and capixaba is a Tulpi word meaning from Espírito Santo.

Dryadonycteris capixaba is a small Glossophagin Bat, slightly over 55 mm in length, with an elongate snout, lacking lower incisors, having a triangular noseleaf and having tricoloured banding of its fur (i.e., each hair has a pale middle band and darker basal and distal bands). The Bats were captured in ground-level mist nets in both dry and wet seasons. The areas where they were captured have been sampled for Bats extensively, implying these are quite rare animals. The forests if Floresta Nacional de Goytacazes are quite badly fragmented, suggesting that Dryadonycteris capixaba may be able to cope with such conditions.

Dryadonycteris capixaba. Nogueira et al. (2012).

See also New species of Bat discovered in Vietnam and Mammals on Sciency Thoughts YouTube.

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What killed the Australian Thylacine.

The Thylacine, also known as the Tasmanian Tiger or Marsupial Wolf, was a large, predatory, marsupial mammal which roamed Australia from about four million years ago until about 3500 years ago, when it became extinct on the Australia mainland, though it persisted on the island of Tasmania till the twentieth century. The period when the Thylacine went extinct on the Australian mainland co-insides with the adoption of a number of new technologies by human populations across mainland Australia (but not Tasmania) leading to a rise in human populations across the continent, and also the introduction of Dingos (wild dogs) to mainland Australia (but again, not Tasmania). These two events are both likely to have contributed to the downfall of the mainland Thylacines, though the contribution of each to the eventual extinction has been hard to assess.

A Thylacine, front, and a Dingo, behind. Carl Buell.

Invasive predators can cause problems for their indigenous rivals in a number of ways. Most obviously they often tend to outcompete them. Prey animals that evolved alongside the indigenous predator will have developed methods of avoiding predation by it, but are often unable to cope with the invasive predator, which may use novel, unfamiliar hunting strategies (such as hunting in packs, which Dingos do, but which Thylacines are not thought to have done). This will cause the incoming predator to suppress prey numbers till they have time to adapt to the novel predation methods. This is more damaging still if individual members of the new species have a larger individual prey requirement; again this is likely to have been the case with the placental Dingos being presumed to have had a faster metabolism than the marsupial Thylacines.

Introduced predators can be even more of a threat if they directly attack members of the indigenous species. Predators will often attack and kill members of smaller predatory species with which they compete, even if they do not actually eat the rival species. Like prey items, predators may be particularly vulnerable if they encounter a novel rival species which behaves in ways they have not evolved to counter.

Until now Thylacines have been thought to have been reasonably safe against direct attacks by Dingos, as members of the surviving twentieth century population in Tasmania were too large, with the females matching the largest Dingos in size, and the males being considerably larger.

In a paper published in the journal PLoS One on 2 May 2012, Mike Letnic of the School of Biological, Earth and Environmental Sciences at the University of New South Wales, Melanie Fillios of the Department of Archaeology at the University of Sydney and Mathew Crowther of the School of Biological Sciences at the University of Sydney, discuss the results of a study of subfossil Dingo and Thylacine specimens from the Western Australian Museum, gathered in temperate southwest Australia and the semi-arid Nullarbor region.

This revealed that he Thylacines of southwest Australia and the Nullarbor region were considerably smaller than those of Tasmania, with only the largest males being comparable in size to a Dingo, and the females typically being around half the size. This suggests that any hostile encounters between the solitary Thylacines and the pack-hunting Dingos would have gone very badly for the Thylacines. Even if the Dingos only targeted female Thylacines the effect on the Thylacine population level would have been devastating; most animals can cope with a sharp drop in the number of male animals, but females are essential to maintaining the population.

Skulls from the Western Australian Museum. Left, female Thylacine. Center, male Thylacine. Right, Dingo. All from the Nullarbor region. Scale bar is 5 cm. Letnic, Fillios & Crowther (2012).

Sufficient material was not available from other regions to assess the sizes of Thylacines across continental Australia, but individual teeth from southeast Australia and a partial skull from the Cape Range in the northwest of the continent suggest that the samples from the Western Australian Museum are a better model than those from Tasmania.

See also New species of Velvetfish from the Kimberly Coast of Western Australia, A new Bent-toed Gecko from Western Australia, Possible impact crater in Palm Valley, Northern Territory, Australia, Fishermen targeting tuna in East Timor at least 42 000 years ago, Walking with Giant Wombats and Mammals on Sciency Thoughts YouTube.

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