“Vertebrates represent a pinnacle of evolution, with their intricate nervous systems, complex behaviors, and diverse body plans.” – Dr. Stephen Jay Gould, paleontologist
The origin of the first vertebrates is still a subject of scientific debate and there are several hypotheses constructed around this.
While you’re at it, you may also like – animals without a heart
The most well-accepted one seemed to be the ‘jawless fish hypothesis’, however, there are far more plausible hypotheses proposed by scientists. Read for yourself below!
Jawless fish hypothesis
The first animals to have a backbone were fishes of the class Agnatha that appeared 500 million years ago during the Cambrian period. They had a primitive backbone made of cartilage, which eventually evolved into the bony vertebral column seen in modern fishes and all other vertebrates. This Hypothesis is the “jawless fish hypothesis,” which suggests that the first vertebrates evolved from a group of jawless, filter-feeding organisms known as the ostracoderms.
Other than this, the Conodont, Entoproct, Stem-cell, and Genomic hypotheses are also some hypotheses that have attempted at understanding the evolution of the backbone.
This hypothesis suggests that the first vertebrates evolved from a group of soft-bodied, tooth-like structures called conodonts. Conodonts were present in the fossil record around 500 million years ago and are believed to have been filter feeders.
While the Conodont hypothesis has been influential in the study of vertebrate evolution, it is now generally considered unlikely, as further research has shown that conodonts are more closely related to invertebrates than to vertebrates
This hypothesis suggests that the first vertebrates evolved from a group of burrowing, worm-like animals known as entoprocts. Entoprocts have a notochord-like structure known as a stomochord, which is believed to be a precursor to the vertebral column.
This was given by Scholtz and his team who studied the embryonic development of the entoproct. They proposed that the entoprocts might be a key group in the evolution of the vertebrates, and that the stomochord could be a precursor to the vertebral column. The Entoproct hypothesis remains a subject of ongoing research and debate, it has not gained widespread acceptance in the scientific community.
This hypothesis suggests that the first vertebrates evolved from a group of stem cells that differentiated into different tissues, including the notochord and other structures.
The evolution of these stem cells allowed for the development of new structures and functions, such as the vertebral column and a more complex nervous system, that were not possible in earlier organisms. The Stem-cell hypothesis is supported by recent discoveries in the fields of stem cell biology and genomics, and it is likely to be an active area of research in the coming years
It is an emerging idea that is gaining traction in the scientific community. This hypothesis suggests that the first vertebrates evolved as a result of genetic changes that allowed for the development of new structures and functions, such as the vertebral column and a more complex nervous system.
While the Genomic hypothesis is still being developed and refined, it is likely to be an active area of research in the coming years.
Did you like what you read? Leave a comment and let us know!