93-3 Revolution of mindset: How Paleontologists put aside biases to learn from Opabinia's History

Session: Crossing Borders in the History and Philosophy of the Geosciences

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I will examine Opabinia, what makes it special, the three paleontologists who researched it, and how human fallibility shapes our perspective.

Charles D. Walcott (1850-1927) was the man who discovered the Burgess Shale Lagerstätte, and wrote about many of the organisms inside it. He collected thousands of fossils from 1910 to 1914, being interrupted with lack of funding and the outbreak of World War 1. (Yochelson, 1996) He described his work as “preliminary”. “He never found… time to examine, ponder, ruminate… and eventually publish essential ingredients of a proper study of these complex and precious fossils” (Gould, 1989)

Opabinia was discovered in 1912. Walcot described it as a sexually dysmorphic arthropod, having either a “slender” or a “strong” front nozzle. Both of these statements are wrong. Walcott based his judgement of Opabinia on other animals. Opabinia had a few traits of an arthropod, so it was an arthropod. It had no antenne, but it was an arthropod. Therefore the antenne had a reason for being gone. If small, it is concealed in the crushed head. If large, they may have broken off. Walcott belived only in his circular reasoning and did not consider there may not be antenne at all.

After sixty years, Opabinia was examined again by Harry Whittington (1916-2010). Whittington realized there were never antenne. This pushed Opabinia out of the Branchiopoda class and into an entirely new phylum. Whittington also proved that Opabinia’s “Sexual dimorphism" was an unrelated worm-like fossil on Opabinia’s proboscis. But Whittington also did not know where to put Opabinia, believing it should belong in an entirely separate Phylum. 

The perspective of Opabinia was refined further, with the contribution of Graham Budd, the student of Simon Conway-Morris, who was himself a student of Whittington.

Budd did just as Whittington did, build upon both the mistakes and correct points of previous voices. Whittington’s research was just as much of a reaction to Walcott’s research as it was to Opabinia’s existence. In the section where Whittington divorced Opabinia from the arthropoda phylum entirely, Budd disagreed, citing Opabinia’s segmentation and compound eyes. In 1996 Budd constructed a phylogenetic tree for the Euarthropoda stem group, with Opabinia back in the Arthropoda phylum.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-11149

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