The Tullimonster is not a vertebrate, a conclusion supported by contemporary paleontological research in North America. This tiny enigmatic creature, measuring about 15 centimeters, emerged in the latter half of the 20th century and has long unsettled scientists with its unusual anatomy. More than a hundred fossils have been uncovered, yet experts have struggled to place it on any traditional evolutionary branch. The first discovery occurred at the Mason Creek Paleontological Site in Illinois, where the fossil appears soft-bodied and was pressed into ancient, malleable silt. In 2016, a team in the United States proposed that the tulip-like fossil might be a vertebrate, sparking renewed debate about its true nature.
To investigate the vertebrate theory, researchers led by Tomoyuki Mikami and colleagues analyzed an impressive sample: over 150 tulip monster fossils and more than 70 other specimens from Mason Creek. They employed a laser scanner to generate precise three-dimensional models and used a color-coded system to mark areas with high concentrations of minute irregularities. Computed tomography provided a deeper look at the internal arrangement of the soft tissues and surrounding structures.
The findings challenged the vertebrate hypothesis. The team concluded that the features used to argue for vertebrate affinities did not align with known vertebrate patterns. In particular, the head region shows segmentation that is distinctly separate from the body, a trait that does not map onto any established vertebrate lineage. The researchers emphasize that this separation is a critical clue that the tulip monster falls outside the common vertebrate blueprint.
With the vertebrate path set aside, scientists now face two compelling possibilities. One is that the tulip monster represents a scalpel-like invertebrate chordate, a group that sits near the base of the deuterostome family tree and includes organisms with a chordate-like nervous system but lacking a backbone. The other possibility points to an unusual protostome—the broad category that includes worms and mollusks—highlighting a creature with an unexpected combination of traits that defies easy classification. The current evidence invites a reexamination of early animal evolution and the criteria used to place fossil specimens on the tree of life.
Earlier observations referenced by biologists noted that certain moths possess tails that function in predator avoidance or sensory perception. While those features are not directly comparable to the tulip monster, they underscore how evolutionary paths can converge on superficially similar traits across distant lineages. The tulip monster serves as a reminder that nature often refuses to fit neatly into human categories, urging scientists to refine their methods and remain open to surprising joins of anatomy and function.
Going forward, researchers will likely pursue a combination of high-resolution imaging, comparative anatomy, and targeted fieldwork to gather more specimens and contextual data. The goal is to determine whether the tulip monster represents a truly unique lineage or a misinterpreted arrangement of known body plans. Either outcome will enrich understanding of how early life diversified and how modern classifications can adapt to uncover the complexities hidden in fossil records. The evolving picture will resonate not only with specialists in North America but also with researchers across Canada and the United States, where regional fossil sites continue to offer fresh opportunities to illuminate the history of life on Earth.