Jawless fish — Dartmuthia gemmifera

Geologic period: Late Silurian

Age: Upper Silurian, Ludlow.

Feeding: Specific feeding behavior is not directly established by this skull alone.

Locomotion: Aquatic vertebrate locomotion.

Body plan: Broad mineralized head shield with a more lightly armored body behind it.

Evidence: The armored head shield is direct evidence. Ecology and full-body behavior are reconstructed from osteostracan anatomy.

Why it matters: Dartmuthia shows that early vertebrates evolved elaborate armor before jaws became universal among fishes.

Plain Language Identity: An armored jawless vertebrate belonging to the osteostracans.

What You Are Looking At: A heavily armored head region from a jawless fish.

Ecosystem: Late Silurian aquatic ecosystem.

Preservation: Mineralized dermal head armor.

Open Questions: The fossil should not be given a modern fish jaw or modern fish body proportions.

Source Urls: https://naturalhistory.si.edu/visit/virtual-tour/current-exhibits/deep-time-virtual-tour-fossil-list; https://fossiilid.info/3200

Enrichment Method: SAGE curated research pass; title and scientific name matched; evidence separated from inference

Scientific name: Dartmuthia gemmifera

Evidence / representation: comparative_exact_taxon_visual

comparative_exact_taxon_visual

Oceans Before Dinosaurs: The Rise of Complex Animal Life.

Media license: CC BY-SA 4.0

https://creativecommons.org/licenses/by-sa/4.0