Artistic restoration of Utaurora comosa from the Wheeler Formation, Utah, U.S.A. (Cambrian: Drumian). Credit: Artwork by F. Anthony
In his book Wonderful Life, the late Stephen Jay Gould, previous teacher in the Department of Organismic and Evolutionary Biology at Harvard, promoted the “weird wonder” stem-group arthropods Opabinia and Anomalocaris, found in the Cambrian Burgess Shale, turning them into icons in pop culture. While the “fear of the Cambrian’ Anomalocaris– with its radial mouth and spiny comprehending appendages– is a radiodont with numerous family members, the five-eyed Opabinia— with its unique frontal proboscis– stays the only opabiniid ever found. That is, previously.
An global group of scientists led by Harvard University verify that a specimen formerly thought about a radiodont remains in reality an opabiniid. The brand-new research study in Proceedings of the Royal Society B utilized unique and robust phylogenetic approaches to verify Utaurora comosa as just the 2nd opabiniid ever found and the very first in over a century.
Utaurora comosa from the Wheeler Formation, Utah, U.S.A. (Cambrian: Drumian). Holotype and just recognized specimen, accessioned at the Division of Invertebrate Paleontology in the Biodiversity Institute at the University ofKansas Credit: Photograph by S. Pates
Utaurora comosa, discovered in the 500 million-year-old middle Cambrian Wheeler Formation of Utah, was very first explained in 2008 as a radiodont. Co- lead author Stephen Pates, previous postdoctoral fellow in the Department of Organismic and Evolutionary Biology (OEB) at Harvard, very first experienced the specimen at the University of Kansas Biodiversity Institute & & Natural History Museum while a college student. Pates was studying the variety of radiodonts and felt this specimen did not precisely fit with a real radiodont. Upon signing up with senior author Professor Javier Ortega-Hern ández’s laboratory in OEB, Pates dealt with co-lead author Jo Wolfe, postdoctoral fellow in OEB who studies the relationships of fossil and living arthropods, to figure out where Utaurora finest fit in the tree of life.
Opabiniids are the very first group to have a posterior-facing mouth. Their dorsal intersegmental furrows are precursors to complete body division and their lateral swimming flaps precursors to appendages. Utaurora shares characters and morphology with both radiodonts and Opabinia While Utaurora’s anterior structure and eyes were badly maintained– Opabinia is most identifiable from its frontal proboscis and 5 eyes, the intersegmental furrows along the back and the paired serrated spinal columns on the tail were completely observed.
Limited morphological observations led Pates and Wolfe to utilize phylogenetic analysis comparing Utaurora with 43 fossils and 11 living taxa of arthropods, radiodonts, and other panarthropods.
“The preliminary phylogenetic analysis revealed it was most carefully associated to Opabinia,” Wolfe stated. “We followed up with more tests to interrogate that result using different models of evolution and data sets to visualize the different kinds of relationships this fossil may have had.”
Unlike Opabinia, which was found in the Cambrian Burgess Shale of British Columbia in Canada, Utaurora was discovered in Utah and, though still Cambrian, is a couple of million years more youthful than Opabinia “This indicates Opabinia was not the only opabiniid, Opabinia was not as special a types as we believed,” Pates stated.
When Utaurora was very first referred to as a radiodont in 2008 researchers believed opabiniids and radiodonts formed a monophyletic group called ‘dinocarids.’ But over the past 10 to 15 years researchers have actually found over 10 brand-new types of radiodonts, making it possible to see that opabiniids and radiodonts are somewhat various.
“We also have more phylogenetic tools to interrogate our results,” Pates stated. “Based on the morphology alone you might make a case for Utaurora being a strange radiodont and likewise for reviving the ‘dinocarid’ idea. But our phylogenetic dataset and analyses supported Utaurora as an opabiniid in 68% of the trees recovered by examining the information, however just in 0.04% for a radiodont.”
“Wonderful Life and the description of these fossils occurred prior to present evolutionary paradigms. The resemblances in between Opabinia and Anomalocaris weren’t truly comprehended yet,” Wolfe stated. “Now we know that these animals represent extinct stages of evolution that are related to modern arthropods. And we have tools beyond qualitatively comparing morphological features for a more definitive placement within the animal tree of life.”
Reference: “New opabiniid diversifies the weirdest wonders of the euarthropod stem group” by Stephen Pates, Joanna M. Wolfe, Rudy Lerosey-Aubril, Allison C. Daley and Javier Ortega-Hern ández, 9 February 2022, Proceedings of the Royal Society B Biological Sciences
DOI: 10.1098/ rspb.20212093
Funding was offered by the Alexander Agassiz Postdoctoral Fellowship (Museum of Comparative Zoology at Harvard) and a Herchel Smith Postdoctoral Fellowship (University of Cambridge). Additional assistance was offered by the National Science Foundation (DEBORAH-1856679).
This research study highlights the extraordinary worth of museum collections for helping with brand-new clinical discoveries. Co- lead authors Pates and Wolfe wish to thank the Division of Invertebrate Paleontology in the Biodiversity Institute at the University ofKansas “We are blessed to have been the home to professors Dick Robison and Bert Rowell and their student Margaret (Peg) Rees, who are experts on rocks and fossils of the Cambrian system; they along with the Gunther family collected numerous important fossils now housed here. These specimens are an invaluable resource for paleontologists to study and can lead to exciting results and discoveries of the type presented here in this important new paper by Pates, Wolfe et al.” Said Professor Bruce Lieberman, Senior Curator.
