The Field Museum blog has a reply to the recent Tully Monster paper that disagreed with the determination of the Tully Monster as a vertebrate, which appeared in a couple papers published last year in Nature.

Last year, two papers in the journal Nature sought to resolve what group of animals Tully Monster fossils belong to; both papers concluded the vertebrates. Last week, Dr. Lauren Sallan and colleagues published a paper in the journal Palaeontology, “The Tully Monster is Not a Vertebrate…” And that’s okay; it is part of how science works.

It’s quite normal for new ideas, based on new scientific information and analyses, to raise questions. You might think of scientific discourse as a marketplace of ideas, backed up by data, analyses, and interpretations. Scientists sometimes disagree about one or more of these three components, and that’s where the marketplace concept comes in. Other scientists (not just the ones who wrote the papers) are part of the marketplace, and they scrutinize the different perspectives, sometimes doing more research, critiquing, or adding to the discussion and building on the base of knowledge about whatever controversy is at hand. Most often, some sort of consensus is reached in the broader scientific community, though it might take years of back-and-forth discussions.

We are co-authors on one of the papers in Nature, and we took part in a long meticulous slog examining more than 1,000 Tully monster fossils in The Field Museum’s collection. We were looking for biologically informative characters to add to the ones that had been reported in the 50-plus year interval since the Tully monster was described as a bizarre beast that didn’t fit into any known animal group. We also examined and looked for characters of other 307-million-year-old Mazon Creek fossils preserved in the same unusual ironstone concretions as the soft-bodied Tully monster.