Follow
A team led by researchers at the University of California discovered the first fossil of an amphibious ichthyosaur in China. This basically means that the discovery is the first to link the dolphinlike ichthyosaur to its terrestrial ancestors, thus filling a gap in the fossil record. The fossil is described in a paper published in advance online Nov. 5 in the journal Nature.
The ichthyosaur, whose discovery was announced Wednesday, fills a crucial gap in the evolution of these dolphin-like predators, which thrived in Jurassic seas about 200 million to 145 million years ago. The reptiles could grow to 65 feet in length, about as long as a tractor-trailer.
“We finally got this milestone and this first ichthyosaur,” said paleontologist Da-yong Jiang of Peking University in Beijing, who co-led the study.
The creature, named Cartorhynchus lenticarpus, was 16 inches (40 cm) long and had a short snout it may have used for suction feeding of creatures like worms from the seabed. The fossil, excavated in 2011 in China’s Anhui province, is quite well-preserved, with only part of the tail missing.
“Cartorhynchus represents a stage of the land-to-sea transition that was somehow lacking in the fossil record of the ichthyosaur lineage, while known in most other marine reptile and mammal lineages,” said University of California-Davis paleontologist Ryosuke Motani, the other study co-leader.
“The fossil that we found is the first to fill this gap in the fossil record,” Motani added. “This is particularly important because some creationists tried to use ichthyosaurs as a counterexample against Darwinian evolution since the group lacked this record.”
Motani further reported that he is looking for more fossils to improve the record and is also willing to find out the direct ancestors of Cartorhynchus lenticarpus. He suspects that those ancestors would be amphibians as well, but spent more time on land.
The research also shed light on how life bounced back four million years after the Permian-Triassic mass extinction, the scientists said. Sometimes called “the Great Dying,” the event wiped out the vast majority of sea species and terrestrial vertebrates, according to the fossil record. The cause has been much debated. One theory is runaway global warming, possibly caused by the escape of methane gas from the sea floor.
