Rare fossils of giant rodents raise questions

Date: February 22, 2017

Source: Taylor & Francis Group

Adult and juvenile remains of a giant rodent species (Isostylomys laurdillardi) have been uncovered by researchers, in the Río de la Plata coastal region of southern Uruguay, raising questions about classification within dinomids.

The study, detailed in Journal of Systematic Palaeontology, consisted of examining teeth structure and development, and comparing the fossils to previously found examples and the largest living rodent -- the capybara. It was proposed that, due to similarities in the adult's and the juvenile's teeth structure, previously found fossils, which were smaller and thought to belong to a different species, were in fact from the same species.

The authors have consequently proposed that members of the subfamily Gyriabrinae could represent juveniles belonging to other subfamilies of Dinomyidae and that three known species of the genus Isostylomys should be merged into just one species, Isostylomys laurillardi.

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Two New Enigmatic Spider Species With Peculiar Living Habits from Uruguay

Oct. 3, 2013 — The two new species described from Uruguay, Chaco castanea and Chaco costai, are middle sized spiders that range between 1 and 2 cm in body size. Like all Nemesiids they have elongated body and robust legs with predominantly black-brownish coloration. A recent study in the open access journal Zookeys provides a detailed description of the two news species and a rare glimpse into their living habits.

The two new species are typically found in sandy soils of oceanic and river coastal areas associated with psammophyte, or sand-dwelling, vegetation. This is where these peculiar spiders build their silk-lined burrow where they spend great deal of their lives. The burrows are also protected by a flap-like door that makes them particularly hard to find.

"Due to a number of life history characteristics, these spiders are difficult to collect and consequently little is known about their biology,"comments Laura Montes de Oca, Instituto de Investigaciones Biológicas Clemente Estable, Uruguay. "Observations in natural conditions let us to know that they are mostly active during night. This knowledge is key to finding the spiders in order to perform the necessary studies, both on field and in laboratory. Remaining in the burrow most of their lives, makes these animals vulnerable to habitat perturbations. In Uruguay the psammophyte vegetation is critically decreasing, so it is very important to study and conserve the species"

Experiments in laboratory environment reveal some of the secrets that the secluded burrow life of these spiders hide.Chaco costai was observed during hunting, when the spiders lift the entrance of the burrow with their front legs. The flap-like door of the spider den provides a perfect cover to ambush and catch the unsuspecting victim. The spiders return to their burrow after catching the prey. Another occasion when the spiders go in the open is during copulation when both the male and the female leave their hiding places. However, they return to the burrows straight after that.

http://www.sciencedaily.com/releases/2013/10/131003111202.htm

Glow-in-the-dark Sheep: Genetically Modified At Uruguay Lab [VIDEO]

Scientists in Uruguay have genetically modified sheep to glow in the dark. The fluorescent sheep are a world first, the scientists report.

The flock of nine lambs was born last October at a farm belonging to the Animal Reproduction Institute of Uruguay, an nonprofit organization affiliated with the Pasteur Institute's genetically modified animals unit. The laboratory incorporated a green fluorescence protein into the genes of the sheep, which will glow when exposed to certain ultraviolet light, making the the ruminants easily identifiable as genetically modified.

Other than glowing green in UV light, the sheep look and behave normally. Scientists modified the sheep's genes with the fluorescent protein of the Aequarea jellyfish.

"We did not use a protein of medical interest or to help with a particular medicine because we wanted to fine-tune the technique. We used the green protein because the color is easily identifiable in the sheep's tissues," said Alejo Menchaca, the head of the research team.

Continued: http://www.natureworldnews.com/articles/1627/20130427/glow-dark-sheep-genetically-modified-uruguay-lab-video.htm