One of the world’s oldest sea creatures dating back half a billion years, has been unearthed in a desert in the U.S.
The oldest sea squirt ever found on Earth was discovered in an area known as the Badlands of Utah.
Its remains were found in a prehistoric graveyard renowned for preserving soft bodied animals.
The 500-million-year-old creature sheds fresh light on our own evolutionary origins.
It belongs to a wonderfully weird group of marine invertebrates – which are distantly related to mammals.
They can be found today from polar regions to the tropics – floating in the water or attached to rocks, docks or ship hulls.
They are commonly called “sea squirts” because when the barrel-shaped animals are touched they tense up – and then squirt water from their siphons.
Badlands National Park contains one of the world’s richest fossil beds, allowing scientists to study the evolution of mammal species such as horses, rhinos and sabre-toothed cats.
Megasiphon thylakos lived on the seabed during the Cambrian – a period of rapid evolution when most major animal groups first appear on Earth.
It was a stationary, filter-feeding adult – after undergoing metamorphosis from a tadpole-like larva.
One siphon drew in water with food particles through suction, allowing the animal to feed using an internal basket-like filter device. Afterwards the other siphon expels the water.
Most sea squirts begin their lives mobile and resembling a tadpole, then change into a barrel shaped adult attached to the seafloor.
Tunicates are also the closest relatives of vertebrates which includes fish, mammals – and even humans.
They are key to understanding our own history. Unfortunately, they are almost completely absent from the entire fossil record.
The main feature that stood out to the Harvard University team were the dark bands running up and down the fossil’s body.
High powered images of Megasiphon allowed the researchers to conduct a side-by-side comparison to a modern counterpart called Ciona – using dissected sections.
Comparisons revealed remarkable similarities between Ciona’s muscles that open and close its siphons and the dark bands observed in the 500-million-year-old fossil.
Dr. Nanglu said: “Megasiphon’s morphology suggests to us that the ancestral lifestyle of tunicates involved a non-moving adult that filter fed with its large siphons.”It’s so rare to find not just a tunicate fossil, but one that provides a unique and unparalleled view into the early evolutionary origins of this enigmatic group.”
“This is an incredible find as we had virtually no conclusive evidence for the ancestral modes of life for this group before this.”
Utah was located near the equator during the Cambrian, so the water temperature was warm. The combination of warm, shallow water and nutrient-rich silt enabled a highly diverse fauna.
After collecting hundreds of new fossils again this spring, the researchers are convinced the site known as the Marjum Formation has only started to reveal its secrets.
Produced in association with SWNS Talker
