A new species of giant clam has been discovered in the Red Sea. Fossils suggest that, about 125,000 years ago, the species Tridacna costata accounted for more than 80% of the area's giant clams. The species may now be critically endangered, researchers report in Current Biology journal.
Diversity among the ancestors of such marine creatures as clams, sand dollars and lobsters showed only a modest rise beginning 144 million years ago with no clear trend afterwards, according to an international team of researchers. This contradicts previous work showing dramatic increases beginning 248 million years ago and may shed light on future diversity.
"Some of the time periods in the past are analogies for what is happening today from global warming. Understanding what happened with diversity in the past can help us provide some prediction on how modern organisms will fare. If we know where we have been, we know something about where it will go" - Jocelyn Sessa, doctoral candidate in geosciences, Penn State.
Using contemporary statistical methods and the Paleobiology Database, the researchers report, in today's (July 4) issue of Science, a new diversity curve that shows that most of the early spread of invertebrates took place well before the Late Cretaceous, and that the net increase through the period since, is proportionately small relative to the 65 million years that elapsed.