OBJECT DOSSIER · SMITHSONIAN OPEN ACCESS

Marine crocodile relative — Steneosaurus bollensis

SAGE Museum Deep Time scientific dossier

Artist / Creator

Daderot

Date / Period

Early Jurassic — Toarcian · Approximately 183 to 181 million years ago for the classic lower-Toarcian Posidonia Shale material.

Object Type

body fossil

Medium

unknown_needs_review

About This Object

Geologic period: Early Jurassic — Toarcian

Age: Approximately 183 to 181 million years ago for the classic lower-Toarcian Posidonia Shale material.

Feeding: Current biomechanical work supports a relatively generalist feeding system rather than an extremely specialized crushing bite.

Locomotion: Adapted to aquatic and shoreline environments; recent work suggests more amphibious capability than older reconstructions sometimes implied.

Body plan: Long narrow skull, elongated body, limbs and rows of protective osteoderms.

Evidence: Extensive skeletons document anatomy. Taxonomic revision comes from modern comparison and phylogenetic analysis.

Why it matters: This specimen lets SAGE show science correcting itself. The old museum name survives in historical records, while modern revision resurrected the genus Macrospondylus.

Plain Language Identity: An Early Jurassic teleosauroid crocodylomorph historically called Steneosaurus bollensis and now recognized as Macrospondylus bollensis.

Current Scientific Name: Macrospondylus bollensis

What You Are Looking At: Fossil material from a long-snouted armored teleosauroid crocodylomorph.

Ecosystem: Early Jurassic coastal environments of western Europe.

Formation: Posidonienschiefer Formation for classic German material.

Find Location: Germany and other parts of western Europe.

Preservation: Fossil skeletal material.

Research History: Steneosaurus became a taxonomic wastebasket. Modern revision re-established Macrospondylus bollensis as a valid species.

Open Questions: Keep the historical Smithsonian inventory name for provenance but show Macrospondylus bollensis as the current scientific name.

Source Urls: https://naturalhistory.si.edu/visit/virtual-tour/current-exhibits/deep-time-virtual-tour-fossil-list; https://link.springer.com/article/10.1007/s12542-024-00712-x

Enrichment Method: SAGE curated research pass; title + scientific name + source scene matched; historic taxonomy retained where relevant; evidence separated from inference

Scientific name: Steneosaurus bollensis

Evidence / representation: comparative_taxon_visual

Why It Is In This SAGE Exhibit

comparative_taxon_visual

Jurassic Giants: Size, Teeth, Armor and Survival.

Provenance

Smithsonian Deep Time source scene: Stegosaurus Spikes vs. Ceratosaurus Claws

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

Steneosaurus bollensis Early Jurassic — Toarcian body fossil Stegosaurus Spikes vs. Ceratosaurus Claws Jurassic Giants

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 ↗