Yunnanozoans are oldest and most primitive vertebrates, researchers conclusively identify

A team of scientists has determined that the fossil record of yunnanozoans, an extinct creature that lived 518 million years ago during the Cambrian period, is the oldest known vertebrate. Primitive vertebrates refer to organisms that were once vertebrates, i.e. with a spine, but are now extinct although there are closely related vertebrates. Vertebrates include all mammals, birds, reptiles, amphibians, and fish, but the vast majority of complex animal life is invertebrates, i.e. do not possess a spine. Scientists have for years puzzled over the missing link to the evolution from invertebrates to vertebrates.

Now, a research team from the Nanjing Institute of Geology and Paleontology, the Chinese Academy of Sciences and Nanjing University, has determined What is the oldest known vertebrate? Team published Their findings are published in the journal Science, on July 8.

The team examined newly collected yunnanozoans, so named for their presence in Yunnan Province, China, fossil samples using high-resolution metastructural and anatomical studies. high and geochemical studies using well-preserved carbon remains on fossils.

Using X-ray microscopy, scanning electron microscopy, transmission electron microscopy, Raman spectrometry, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy, the team confirmed that the fossils have tissue cells in the pharynx, a distinguishing feature of vertebrates. The scientists discovered that the pharynx in yunnanozoans has seven identical arches, sharing bamboo-like segments and fibers connected by crossbars on the back and abdomen, forming a basket – a trait today is now found in live jawless fish.

Researchers have long hypothesized that the pharyngeal arches, which are responsible for creating the structures of the face and neck, played a large role in early vertebrate evolution.

“Two types of pharyngeal bones — the basket type and the isolated type — occurred in vertebrates and in Cambrian living. This implies that the pharyngeal skeleton has a more complex early evolutionary history than one might think,” said Tian Qingyi, first author of the study.