South Africa: world’s oldest fossil lamprey found

From BuaNews in South Africa:

Scientists from the University of the Witwatersrand and the University of Chicago have discovered a 360 million-year-old lamprey.

The discovery was made at Witteberg Group rocks near Grahamstown, in the Eastern Cape.

According to the scientists, this demonstrated that modern lampreys are remarkable living fossils.

The report is published in Nature today.

This jawless fish fossil was discovered by Robert Gess, a PhD student at the Bernard Price Institute for Palaeontological Research at Wits, under the supervision of Professor Bruce Rubidge of Wits and Dr Mike Coates of the University of Chicago.

Scientists from around the world are currently engaged in reconstructing the evolutionary tree of life, combining data from the structure of living organisms, the fossil record and the analysis of DNA.

A statement from Wits University said in ancient seas, jawless vertebrate fish predated and gave rise to jawed fish, from which all vertebrates, including humans, descended.

The only surviving group of jawless vertebrates are the lampreys which, as a result, are attracting intense scientific interest.

Only in living lampreys may jawless vertebrate embryology or DNA be studied, resulting in lampreys being increasingly used as surrogate ancestors in researching jawed vertebrates.

“Lampreys are, however, highly specialised for a parasitic existence, sucking onto living fish, using a disc that surrounds their circular mouth, to feed on blood and tissue with the aid of a rasping tongue,” said the university.

“Knowing when lampreys acquired this specialization, would suggest how representative they really are of ancient fish.”

The boneless cartilagenous skeletons of lampreys have, however, left virtually no fossil record – only three fossil species having previously been described, in none of which is a sucker-disc visible.

The remarkably well-preserved new fossil, described in the prestigious scientific journal Nature, is older than any previously discovered fossil lamprey by 35 million years.

Only 42mm long, it reveals details of its fin, gill basket and, most importantly, its mouth region.

Its circular mouth, situated at the centre of a large sucker disk and encircled by small teeth, is remarkably like that of living lampreys, revealing that lamprey adaptations for a blood-sucking lifestyle were acquired in ancient seas, before modern fish faunas arose.

Lampreys are therefore “living fossils” that have remained largely unaltered through more than 360 million years and four major extinction events.

The fossil has been named Priscomyzon riniensis (from Latin prisco (ancient) myzon (a lamprey) and Rini, the Xhosa name for Grahamstown and surrounds.

See also here.

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