Scientists believe an ancient armored shark that swam in our oceans 436 million years ago is our oldest jawed ancestor.
Recently, scientists found tiny fragments in China that belonged to a creature with external body ‘armor.’ It also had several pairs of fin spines.
In addition to the armored shark, the team also found about 20 teeth from this new species dubbed Fanjingshania. As a result, they determined they could have only come from a fish with a jaw similar to today’s sharks.
According to scientists, “the fossils help to trace many human body structures back to ancient fishes, some 440 million years ago. They added, they “fill some key gaps in the evolution of from fish to human.”
Corresponding author Professor Zhu Min, said: ‘This is the oldest jawed fish with known anatomy.
“The new data allowed us to place Fanjingshania in the family tree of early vertebrates and gain much-needed information about the evolutionary steps leading to the origin of important vertebrate adaptations such as jaws, sensory systems, and paired appendages.”
In 2013, scientists said they found a 419-million-year-old fish fossil in China that debunked the theory that today’s animals with bony skeletons evolved from an animal with a cartilage frame.
Paleontologists make major discoveries, find armored shark and other ancient creatures
Fanjingshania had several characteristics that differ from any recorded vertebrate, specifically dermal shoulder girdle plates that fuse to several spines.
However, the reptile’s fin spines are among the most significant findings. The feature helped scientists find the new species’ position in the evolutionary tree of our ancient creatures.
The researchers also said that Fanjingshania’s bones reveal resorption. This is the absorption of cells or tissue into the system, and remodeling, usually seen in fish’s skeletal development.
The resorption features of Fanjingshania are highest in its trunk scales. It shows the shedding of crown elements and removal of dermal bone from the scale base.
According to the Lead author, Dr. Plamen Andreev, “This level of hard tissue modification is unprecedented in chondrichthyans.” He added: “It speaks about greater than currently understood developmental plasticity of the mineralized skeleton at the onset of jawed fish diversification.”
The team also discovered the skeleton of galeaspids. These are an extinct group of jawless marine and freshwater fish, in the rocks of Hunan Province and Chongqing.
Up until now, only fossils of the creatures’ heads have been found. These remains also reveal the first time paired fins evolved.
First author Zhikun Gai, a University of Bristol alumnus, said: ‘The anatomy of galeaspids has been something of a mystery since they were first discovered more than half a century ago.
‘Tens of thousands of fossils are known from China and Vietnam, but almost all of them are just heads. Nothing has been known about the rest of their bodies, until now.”