Sea squirts are a group of vertebrates, meaning they share a common ancestor hundreds of millions of years ago. (Image credit: Magdevski/Getty Images)
Amazingly preserved half-billion-year-old fossils of strange Cambrian creatures could transform our understanding of how sister groups evolved into vertebrates, a new study has found.
The fossil described July 6 in the journal Nature Communications is the oldest of its kind and belongs to an ancient tutra species, Megasiphon thylakos. The discovery answers fundamental questions about what the earliest tulips looked like, filling in an important gap in the tree of animal life.
Newly discovered fossils provide “the best window into what early tunicates were like, how they lived, what their environment was like, and their lifestyle, which in turn allows us to make some conclusions about what early vertebrates and early vertebrates may have had in general,” study the co-authors Karma Nangloa postdoctoral fellow at Harvard University’s Museum of Comparative Zoology, told Live Science.
Tunic is sister group They are vertebrates, meaning they share a common ancestor hundreds of millions of years ago. They are a diverse subgroup of animals that includes marine invertebrates 3000 species modern. They fall into two distinct groups: attachments and attachments. Often called “sea squirts”, they start life as tadpole-like forms, attaching themselves permanently to the ocean floor before evolving into barrel-like adults. Pedipids retain their tadpole morphology into adulthood and continue to swim in the water column. Until recently, it was unclear whether the first appendages were appendages or appendages—a question that is also important for understanding the evolutionary origin of vertebrates, given their close relationship to reptiles.
Related: Did the Cambrian Explosion really happen?
We know so little about ancient scavengers because we have only one fossil from this early period of their history: a strange creature unlike modern scavengers called chankoclava, which was discovered two decades ago in China. Nanglu said the fossil may be rare because the glabella is relatively rare, or perhaps simply because its soft body is not well preserved.
evolutionary clues
Study co-authors Javier Ortega Hernandez And Rudy Lerosi-Obriel, an assistant professor of organic and evolutionary biology and research associate at Harvard University, discovered the newly described fossil in a collection held at the Utah Museum of Natural History. Nanglu identified the tunic-like features: a barrel-shaped body and sword-like growth, especially the dark stripes that marked the body.
The team examined the fossils using a microscope and high-resolution imaging, and compared the fossil’s anatomy to that of modern Asadacea species. The autopsy confirmed that the structural similarities between the two were not just superficial. In fact, the dark bands represent a similar muscle arrangement between the two M thylaco and its modern counterpart.
“What this tunic tells us is that the ancestor was probably an animal that had a lava-like shape like a tadpole and then turned into a barrel-shaped animal and these two siphons went into the water column,” said Nangluo.
In other words, this two-stage lifestyle most likely originated in the tunic. The findings also place the origin of tunicates at around 500 million years ago, not far from estimates made using “molecular clocks,” or mutation rates in DNA, the study authors wrote in the paper.
The identification of the fossil, which was originally discovered in the middle of the Margum-Cambrian Formation in Utah, raises the question of whether the appendix or appendix was the first to branch off the tunic tree of life. similarity M thylaco He showed Ascidia that the ascetic body form was ancestral, a hypothesis he supports in recent research.
In the follow-up work, Nanglu wants to find fossils that can reveal the point when deuterostomes formed, which include chordates (including tunicates and vertebrates), hemichordates (including worm-like marine organisms), and echinoderms (such as starfish and sea cucumbers). . ), reveals the point connecting them all in an evolutionary sense.
“We are still looking for other animals that fit into this tree of life,” said Nanglo.
2023-07-18 11:53:56
#Fossils #strange #creatures #dating #years #Cambrian #period #offer #evolutionary #clues #vertebrates
