Washington, Oct 25 (IANS): Scientists have discovered a new species of coelacanth fish whose tiny pieces of fossil skull are 100 million years old.

The coelacanth has one of the longest lineages, 400 million years, of any animal. The discovery, made in Texas, is significant because it is most closely related to vertebrates, including humans.

The Southern Methodist University (Dallas) specimen is the first coelacanth in Texas from the Cretaceous (period), extending from 146 million years ago to 66 million years ago, said John F. Graf, the palaeontolgist who identified the fossil and named it 'Reidus hilli'.

Previously, the youngest was a 200 million-year-old coelacanth from the Triassic. 'Reidus hilli' is the first coelacanth ever identified from the Dallas-Fort Worth area, according to a Southern Methodist statement.

Coelacanth fossils have been found on every continent except Antarctica. The species has eluded extinction for 400 million years.

Scientists estimate the coelacanth reached its maximum diversity during the Triassic.

The coelacanth was thought to have gone extinct about 70 million years ago. That changed, however, when the fish rose to fame in 1938 after live specimens were caught off the coast of Africa. Today, coelacanths can be found swimming in the depths of the Indian Ocean.

"What makes the coelacanth interesting is that they are literally the closest living fish to all the vertebrates that are living on land," Graf said.

"They share the most recent common ancestor with all of terrestrial vertebrates."