Missing creatures fill the amazing void in the fossil record

Missing creatures fill the amazing void in the fossil record

Yunnanozoan Art Reconstruction

The artistic restoration of the Yunnan Youth from the Cambrian Qingjiang Biota shows a pharyngeal skeleton like a basket. Credit: Dengwa Yang

Research reveals Greek youth as one of the oldest known stem phrases.

The new findings answer questions in the fossil record.

The astonishing gap in the fossil record that would explain the evolution of vertebrates to vertebrate animals has long worried scientists. Poor animals have unique characteristics, such as spines and skulls, and include fish, amphibians, insects, birds, mammals, and humans. On the other hand, there are non-vertebrate animals without spinal bones.

The process by which non-vertebrate animals moved into the verb – and what this first verb seems to be – has been a mystery to scientists for centuries.

A team of scientists has now studied the disappearances of unicorns since the beginning of the Cambrian period (518 million years ago), and found evidence that they are the oldest known spinal cord. Stem vertebrate is a term that refers to vertebrates that have been destroyed, but are closely related to living vertebrates.

The scientists, from the Nanjing Institute of Geology and Paleontology, the Chinese Academy of Sciences, and Nanjing University, published their findings in the July 7, 2022 journal. Science.

Stem vertebrate Yunnanozoan

Stem vertebrate yunnanozoan. Credit: Fangchen Zhao

Over the years, as researchers have studied how vertebrate animals evolve, a key focus of research has been the pharyngeal arch. These are the structures that produce parts of the face and neck, such as muscles, bones, and connective tissue. Scientists have hypothesized that the vertebral arch evolved from an unconnected cartilaginous rod in the forefathers of the vertebrae, such as the cordite amphotericus, which is a close relative of the vertebrae. However, whether such anatomy actually existed in ancient ancestors is not known for certain.

In an effort to better understand the role of the pharyngeal arch in ancient phrases, the research team studied soft-bodied Greek fossils found in Yinnan Province, China. For years, researchers have studied eukaryotes, with different conclusions about the anatomy of creatures. The relevance of the Greeks has been debated for nearly three decades, with many articles published supporting different views, including four. Nature And Science.

The research team examined newly collected unicellular fossil samples that had not previously been discovered, conducting high-resolution anatomical and ultra-structural studies. The 127 samples they studied were well-preserved carbonaceous residues which allowed the team to perform ultra-structural observations and detailed biochemical analyzes.

The team applied X-ray microscopy, scanning electron microscopy, transmitting electron microscopy, Raman spectrometry, foyer-transform infrared spectroscopy, and energy-distributing X-ray spectroscopy to the fossil samples. Their study confirmed in many ways that unicellular nerve cells have a cell membrane, a feature that is considered specific to the phrase. The team’s findings support the idea that the young are the backbone of the stem. The results of their study show that the Yunanzoans are the earliest and most primitive relatives of the crown group vertebrae.

During their study, the team observed that all seven pharyngeal arches in the Greek fossils were identical to each other. All altars have bamboo-like sections and filaments. The neighboring arches are all connected by door and ventral horizontal rods, which form a basket. The basket-like pharyngeal skeleton is a feature found in living inanimate fish today, such as limpers and egg fish.

“Two types of neural skeletons – cloth-like and isolated types – occur in the cambrian and living vertebrae. This means that the neural skeletal shape has a more complex early evolutionary history than ever before,” said the Chinese Academy of Sciences. Tian Qingyi, the first author of the study from Nanjing University and the Nanjing Institute of Geology and Paleontology, said.

Their research team provided new insights for the detailed structures of the pharyngeal arches. The new anatomical observations that the team has obtained in their research support the placement of the evolution of the unicorns in the fundamental part of the vertebrate tree of life.

Reference: “Ultrastructure Reveals Nerve Spinal Cord Skeleton in Yunnanozoans” by Qingyi Tian, ​​Fangchen Zhao, Han Zheng, Mawian Zhou and Biojiang, July 7, 2022, Science.
DOI: 10.1126 / science.abm2708

The research team includes Qingyi Tian from Nanjing University (NJU) and Nanjing Institute of Geology and Paleontology, Academy of Sciences of China (NIGPAS); Fengchin Zhao and Han Zheng from NIGPAS; Maoyan Zhu from NIGPAS and University of China Academy of Sciences; And Biojiang from NJU.

The study was funded by the Strategic Priority Research Program (BAP) of the Chinese Academy of Sciences and the China National Science Foundation.

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