Bohaskaia monodontoides
March, 23, 2012 -- Beluga whales and narwhals live solely in the cold waters of the Arctic and sub-arctic. Smithsonian scientists, however, found that this may not have always been the case. They recently described a new toothed whale, a close relative of today's belugas and narwhals, that lived some 3-4 million years ago during the Pliocene in warm water regions.
Why and when its modern-day relatives evolved to live only in northern latitudes remains a mystery. The team's research was recently described in the Journal of Vertebrate Paleontolog.
This new whale, Bohaskaia monodontoides, is known only from a nearly complete skull found in 1969 in a mine near Hampton, Va.
Since its discovery, the skull has been housed in the paleontology collections of the Smithsonian's National Museum of Natural History. It was loosely identified as belonging to a beluga whale but it had never been closely studied.
In 2010, Jorge Velez-Juarbe, Smithsonian predoctoral fellow from Howard University, and Nicholas Pyenson, research geologist of the Smithsonian's National Museum of Natural History began a close anatomical comparison of the fossil skull with the skeletons of belugas and narwhals in the Smithsonian's collection.
Their study confirmed that the fossil skull was that of a new toothed whale — one that shared features of the snout and face with belugas and narwhals. The fossil skull contained enough unique features however, to convince the researchers that it would be reasonable to erect a new genus.
"Fossils referred to as belugas have been known from fragmentary bits, but skulls are so revealing because they contain so many informative features," Pyenson says. "We realized this skull was not something assignable to a beluga, and when we sat down, comparing the fossil side by side with the actual skulls of belugas and narwhals, we found it was a very different animal."
As Bohaskaia monodontoides was found in the temperate climate of Virginia, and a second extinct beluga-related toothed whale, Denebola branchycephala is known from a fossil found in Baja California, Velez-Juarbe and Pyenson think that the cold-climate adaptations of narwhals and beluga, which today live and breed only in the Arctic and sub-arctic, must have evolved only recently.
"The fact is that living belugas and narwhals are found only in the Arctic and subarctic, yet the early fossil record of the monodontids extends well into temperate and tropical regions," Pyenson says. "For evidence of how and when the Arctic adaptations of belugas and narwhals arose we will have to look more recently in time."
The change may be "related to oceanographic changes during or after the Pliocene affecting the marine food chain," Velez-Juarbe says, "then competition or dietary preferences drove monodontids further north."
Self-healing hydrogels
Mar. 6, 2012 -- University of California, San Diego bioengineers have developed a self-healing hydrogel that binds in seconds, as easily as Velcro, and forms a bond strong enough to withstand repeated stretching. The material has numerous potential applications, including medical sutures, targeted drug delivery, industrial sealants and self-healing plastics, a team of UC San Diego Jacobs School of Engineering researchers reported March 5 in the online Early Edition of the Proceedings of the National Academy of Sciences. A self-healing substance is one that rebonds to itself when cut.
Hydrogels are made of linked chains of polymer molecules that form a flexible, jello-like material similar to soft-tissues. Until now, researchers have been unable to develop hydrogels that can rapidly repair themselves when a cut was introduced, limiting their potential applications. The team, led by Shyni Varghese, overcame this challenge with the use of "dangling side-chain" molecules that extend like fingers on a hand from the primary structure of the hydrogel network and enable them to grasp one another.
"Self-healing is one of the
