Fossil fish reveal the oldest previously known “jaw”

The most notable specimen at the site is a jawless fish called Tujiaaspis vividus, said Philip Donoghue, a paleontologist at the University of Bristol and author of the paper. Thousands of armor of the species family are known from the fossil record, but Tujiaaspis retains the earliest known body. It came with a surprise: a pair of paired fins protruding from the skull, which Dr. Donoghue and colleagues suggest a possible precursor to the pectoral and pelvic fins found in the gnathostome, which gave rise to the fish’s moving arms and legs. towards the ground. Previously, researchers believed that the two sets of fins evolved separately between jawless and jawless fish.

“This overturns conventional wisdom about how paired complements emerge,” says Dr. Donoghue.

The second site, which is 439 million years old, has preserved more significant fossils. One leaf depicts a cluster of spines, scales and head plates of an animal called Fanjingshania renovata, Everyone dies from the next example of cartilaginous fish. Another registered a spiral of connected teeth – The oldest by far of the vertebrates From a fish called Qianodus dupis. Both animals belong to a branch of jawed fish called chondrichthyes, a group of cartilaginous fish that includes modern-day sharks, rays, and ratfish. (Bony fish like salmon and humans are another offshoot.)

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