"The weirdest wonder of the Cambrian no longer stands alone" is the concluding sentence of a recently released paper regarding a discovery in Utah in Cambrian aged deposits that is now being classified as a relative of the strange creature known as Opabinia regalis.
Until now Opabinia, an extinct, stem group arthropod from the Middle Cambrian Burgess Shale of British Columbia, was so unique (described as "alien-faced") that scientists had never discovered anything else in the fossil record that appears to fit into its family.
Basically, Opabinia was a soft-bodied creature up to 7cm (2¾") long possessing five eyes and a long striped proboscis that resembled an elephant's trunk, or a vacuum cleaner hose, terminating with a claw-like structure that likely passed food to the mouth. -- which was located under the head, behind the proboscis, and pointed backwards. It probably lived on the seafloor, using the proboscis to seek out small, soft food.
But enough about Opabinia. What's new is that researchers apparently discovered a relative that lived a few million years after Opabinia further south in the roughly 507 myo Wheeler Formation in Millard County, western Utah that is called Utaurora comosa.
The creature's first or genus name is a combination of Utah (where the specimen was found) and Aurora (name of a Roman goddess who turned a lover into an insect, and Utaurora is an early species close to the origin of arthropods), while the second or species name is Latin for "hairy" or "leafy" which refers to Utaurora's hairy-looking dorsal surface and leaf-like arrangement of caudal blades on its tail.
Utaurora's tail is spiker than the fan-like one possessed by Opabinia (having nearly twice as many caudal blades) and IIRC the proboscis is missing from the specimen so we don't know what it was like.
Until now it was regarded as potential relative of the apex Cambrian predator -- the Anomalocaris (another bizarre organism from that time). But unlike Anomalocaris, the much smaller Utaurora had no appendages on its head and possessed a body that was segmented into 14 or 15 furrow that were each tipped with a flap -- like what is seen on Opabinia.
This led a team of researchers, led by Stephen Pates of Harvard's Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, to reexamine Utaurora conducting a series of various phylogenetic tests which compared 125 of the fossil’s traits with more than 50 groups of both extant (still living) and extinct arthropods.
The team's analysis allowed them to construct detailed evolutionary trees permitting them to eliminate any relationship with the radiodont family and instead conclude that Utaurora was almost certainly closely related to Opabinia.
The entire paper, New opabiniid diversifies the weirdest wonders of the euarthropod stem group is available for reading at the provided hyperlink, and the abstract from it is below:
Until now Opabinia, an extinct, stem group arthropod from the Middle Cambrian Burgess Shale of British Columbia, was so unique (described as "alien-faced") that scientists had never discovered anything else in the fossil record that appears to fit into its family.
Basically, Opabinia was a soft-bodied creature up to 7cm (2¾") long possessing five eyes and a long striped proboscis that resembled an elephant's trunk, or a vacuum cleaner hose, terminating with a claw-like structure that likely passed food to the mouth. -- which was located under the head, behind the proboscis, and pointed backwards. It probably lived on the seafloor, using the proboscis to seek out small, soft food.
But enough about Opabinia. What's new is that researchers apparently discovered a relative that lived a few million years after Opabinia further south in the roughly 507 myo Wheeler Formation in Millard County, western Utah that is called Utaurora comosa.
The creature's first or genus name is a combination of Utah (where the specimen was found) and Aurora (name of a Roman goddess who turned a lover into an insect, and Utaurora is an early species close to the origin of arthropods), while the second or species name is Latin for "hairy" or "leafy" which refers to Utaurora's hairy-looking dorsal surface and leaf-like arrangement of caudal blades on its tail.
Utaurora's tail is spiker than the fan-like one possessed by Opabinia (having nearly twice as many caudal blades) and IIRC the proboscis is missing from the specimen so we don't know what it was like.
Until now it was regarded as potential relative of the apex Cambrian predator -- the Anomalocaris (another bizarre organism from that time). But unlike Anomalocaris, the much smaller Utaurora had no appendages on its head and possessed a body that was segmented into 14 or 15 furrow that were each tipped with a flap -- like what is seen on Opabinia.
This led a team of researchers, led by Stephen Pates of Harvard's Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, to reexamine Utaurora conducting a series of various phylogenetic tests which compared 125 of the fossil’s traits with more than 50 groups of both extant (still living) and extinct arthropods.
The team's analysis allowed them to construct detailed evolutionary trees permitting them to eliminate any relationship with the radiodont family and instead conclude that Utaurora was almost certainly closely related to Opabinia.
The entire paper, New opabiniid diversifies the weirdest wonders of the euarthropod stem group is available for reading at the provided hyperlink, and the abstract from it is below:
Abstract
Once considered ‘weird wonders’ of the Cambrian, the emblematic Burgess Shale animals Anomalocaris and Opabinia are now recognized as lower stem-group euarthropods and have provided crucial data for constraining the polarity of key morphological characters in the group. Anomalocaris and its relatives (radiodonts) had worldwide distribution and survived until at least the Devonian. However, despite intense study, Opabinia remains the only formally described opabiniid to date. Here we reinterpret a fossil from the Wheeler Formation of Utah as a new opabiniid, Utaurora comosa nov. gen. et sp. By visualizing the sample of phylogenetic topologies in treespace, our results fortify support for the position of U. comosa beyond the nodal support traditionally applied. Our phylogenetic evidence expands opabiniids to multiple Cambrian stages. Our results underscore the power of treespace visualization for resolving imperfectly preserved fossils and expanding the known diversity and spatio-temporal ranges within the euarthropod lower stem group.
Once considered ‘weird wonders’ of the Cambrian, the emblematic Burgess Shale animals Anomalocaris and Opabinia are now recognized as lower stem-group euarthropods and have provided crucial data for constraining the polarity of key morphological characters in the group. Anomalocaris and its relatives (radiodonts) had worldwide distribution and survived until at least the Devonian. However, despite intense study, Opabinia remains the only formally described opabiniid to date. Here we reinterpret a fossil from the Wheeler Formation of Utah as a new opabiniid, Utaurora comosa nov. gen. et sp. By visualizing the sample of phylogenetic topologies in treespace, our results fortify support for the position of U. comosa beyond the nodal support traditionally applied. Our phylogenetic evidence expands opabiniids to multiple Cambrian stages. Our results underscore the power of treespace visualization for resolving imperfectly preserved fossils and expanding the known diversity and spatio-temporal ranges within the euarthropod lower stem group.
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