Yunnanozoan's, alien-like creatures that lived over 518 million years ago turn out to be the oldest-known ancestor to ALL Vertebrates.
It was recently discovered that Yunnanozoans are the oldest known trunk vertebrates, originating in the early Cambrian period (518 million years ago).
The term backbone vertebrate refers to extinct vertebrates that are closely related to living ones.
The findings have been published in the journal Science by researchers from the Nanjing Institute of Geology and Paleontology, the Chinese Academy of Sciences, and Nanjing University.
Pharyngeal arches have become a focus of research as scientists study how vertebrates evolved over the years. These structures produce the muscles, bones, and connective tissue that form the face and neck.
According to research, vertebrate ancestors, such as chordate amphioxus, a distant relative of vertebrates, developed pharyngeal arches from non-articulating cartilage. In ancient times, such anatomy may have existed, but it is unclear whether it did. To find out, researchers decided to use new imaging techniques to get to the bottom of the vertebrates’ mystery.
Researchers studied the fossils of Yunnanozoans — ancient alien-like animals — found in Yunnan Province, China, to understand better how the pharyngeal arch functions in ancient vertebrates.
Yunnanozoans have been studied for years, but different conclusions have been drawn about their anatomy. Several publications, including four in Nature and Science, have supported differing views about Yunnanozoan affinity for around three decades.
Studying previously unexplored Yunnanozoan fossils in high-resolution anatomical and ultrastructural detail was the research team’s goal.
“Our findings on Yunnanozoans support a mainstream hypothesis that ancestors of vertebrates had serially patterned, identical pharyngeal arches, with the first two or three pairs developing into the jaw and hyoid bones.”
“These analyses support that Yunnanozoans are the earliest branching stem vertebrates,” the team wrote in an article published in the peer-reviewed journal Science on Friday.
It was possible to perform detailed geochemical analysis and ultrastructural observations on the 127 specimens that were studied due to well-preserved carbonaceous residues.
Various imaging techniques were used to examine the fossil samples, including X-ray microtomography, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy.
Multiple findings from their study confirmed that Yunnanozoans possess cellular cartilage in their pharynx, a characteristic usually found in vertebrates.
The team’s findings confirm Yunnanozoan backbone vertebrates.
According to their findings, Yunnanozoans represent the first and most primitive vertebrate relatives of the crown group. In addition, researchers discovered that Yunnanozoan fossils had seven similar pharyngeal arches during the study.
Bamboo-like segments and filaments can be found on all bows. A basket-like structure forms when neighboring arches are connected by horizontal rods on the dorsal and ventral sides. Lampreys and hagfish have basket-shaped pharyngeal skeletons, which is common to jawless fish.
“Pharyngeal arches are a key innovation that likely contributed to the evolution of the jaws and braincase of vertebrates,” the researchers wrote.
Researchers gained new insights into the pharyngeal arches due to their investigation. Yunnanozoans have been positioned as the most basal vertebrate taxon in their study, thanks to the team’s new anatomical observations.
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