OBJECT DOSSIER · SMITHSONIAN OPEN ACCESS

Trilobite — Isotelus gigas

SAGE Museum Deep Time scientific dossier

Artist / Creator

Ryan Schwark

Date / Period

Late Ordovician · Late Ordovician; Smithsonian material includes Cincinnatian and Trentonian occurrences.

Object Type

exoskeleton fossil

Medium

original_fossil

About This Object

Geologic period: Late Ordovician

Age: Late Ordovician; Smithsonian material includes Cincinnatian and Trentonian occurrences.

Feeding: Specific feeding behavior is not assigned from this display specimen alone.

Locomotion: Walking across or near the seafloor using paired limbs, known from trilobite anatomy.

Body plan: Broad cephalon, segmented thorax and pygidium forming the classic three-part trilobite body.

Evidence: Exoskeleton anatomy is direct. Limb and behavior reconstructions draw on exceptional trilobite fossils and comparative anatomy.

Why it matters: Isotelus represents one of the most recognizable successful arthropod designs of Paleozoic seas.

Plain Language Identity: A large asaphid trilobite from Ordovician seas.

What You Are Looking At: The mineralized external skeleton of an extinct marine arthropod.

Ecosystem: Ordovician marine seafloor.

Preservation: Mineralized exoskeleton.

Open Questions: A fossil exoskeleton should not be mistaken for the complete original animal including soft tissues.

Source Urls: https://naturalhistory.si.edu/visit/virtual-tour/current-exhibits/deep-time-virtual-tour-fossil-list; https://www.si.edu/object/isotelus-gigas-dekay:nmnhpaleobiology_3021122

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

Scientific name: Isotelus gigas

Evidence / representation: comparative_exact_taxon_visual

Why It Is In This SAGE Exhibit

comparative_exact_taxon_visual

Oceans Before Dinosaurs: The Rise of Complex Animal Life.

Provenance

Smithsonian Deep Time source scene: Early Life in the Ocean

Visual source institution: Wikimedia Commons

Exhibition History

Included in the SAGE Museum Dinosaurs & Deep Time staging exhibit.

Collection & Credit

Media license: CC0

http://creativecommons.org/publicdomain/zero/1.0/deed.en

Subjects & Themes

Isotelus gigas Late Ordovician exoskeleton fossil Early Life in the Ocean Oceans Before Dinosaurs

ORIGINAL COLLECTION SOURCE

This object page stays inside SAGE Museum. The Smithsonian link below is provided only as the original scholarly collection record. It opens separately.

VIEW ORIGINAL SMITHSONIAN RECORD ↗