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A new species of shark that “walks” along the seabed using its fins as tiny legs has been discovered in eastern Indonesia, an environmental group said Friday.
The brown and white bamboo shark pushes itself along the ocean floor as it forages for small fish and crustaceans at night, said Conservation International, whose scientists were involved in its discovery.
The shark, which grows to a maximum length of just 80 centimetres (30 inches) and is harmless to humans, was discovered off Halmahera, one of the Maluku Islands that lie west of New Guinea.
For handful of those believing in evolution, the following figure from this website shows how sharks are related to tetrapods:
How did they evolve to develop walking skills? Maybe the following paper is the answer.
Translated into plain English -
The basic process for developing fingers and toes in land animals may have existed for more than 500 million years in shark genes, according to a new study.
Researchers identified genetic activity in spotted catsharks embryos that signal the creation of digits.
The discovery pushes back the date of the evolutionary “fin to limb” advance by some 135 million years.
When a geneessentially a set of instructionsis translated into a trait, such as red hair or an arm, it is said to be expressed.
Scientists have long believed that the gene for digit development was first expressed some 365 million years ago in the earliest tetrapodsthe first vertebrates to walk on land. (Related: “Ancient Fish Fossil May Rewrite Story of Animal Evolution” [October 18, 2006].)
But the new study suggests the finger-and-toe gene was first expressed much earlier, in fishthough not to such an extent that it yielded actual digits.
“We’ve uncovered a surprising degree of genetic complexity in place at an early point in the evolution of appendages,” study leader Martin Cohn of the University of Florida said in a statement.
The findings appear this week in the journal PLos ONE.
In the context of development of tetrapods from fish, readers may also take a look at the coelacanth genome paper we covered earlier. The paper has an informative section comparing Hox genes in mouse and coelacanth related to limb development.
Also note that a second coelacanth species was discovered near Indonesia in 1999 after everyone thought that the one found in 1930s near Africa was the only living version.
The discovery of a species still living, when they were believed to have gone extinct 65 million years previously, makes the coelacanth the best-known example of a Lazarus taxon, an evolutionary line that seems to have disappeared from the fossil record only to reappear much later. Since 1938, Latimeria chalumnae have been found in the Comoros, Kenya, Tanzania, Mozambique, Madagascar, and in iSimangaliso Wetland Park, Kwazulu-Natal in South Africa.
The second extant species, L. menadoensis, was described from Manado, North Sulawesi, Indonesia in 1999 by Pouyaud et al. based on a specimen discovered by Mark V. Erdmann in 1998 and deposited at the Indonesian Institute of Sciences (LIPI). Only a photograph of the first specimen of this species was made at a local market by Erdmann and his wife Arnaz Mehta before it was bought by a shopper.
Not only that, in 2003, an unknown human form was found in an Indonesian island.
Homo floresiensis (“Flores Man”, nicknamed “hobbit” and “Flo”) is an extinct species in the genus Homo. The remains of an individual that would have stood about three feet in height were discovered in 2003 on the island of Flores in Indonesia. Partial skeletons of nine individuals have been recovered, including one complete cranium (skull). These remains have been the subject of intense research to determine whether they represent a species distinct from modern humans. This hominin is remarkable for its small body and brain and for its survival until relatively recent times (possibly as recently as 12,000 years ago). Recovered alongside the skeletal remains were stone tools from archaeological horizons ranging from 94,000 to 13,000 years ago. It is thought by some that this creature might be at the root of the Ebu gogo myths prevalent on the isle of Flores.
These discoveries suggest that the water and land around Indonesia may have many surprises left.