Middle Jurassic Dinosaurs Codexery

Spicomellus

Oldest definitive ankylosaur with fused osteoderms and tail weapon.

Its most distinctive feature is dermal spikes fused directly to its ribs, a condition unknown in any other vertebrate.[1][2] The genus Spicomellus belongs to the ankylosaurian dinosaur group and its fossils come from Middle Jurassic deposits in Morocco.[3] With an age of roughly 165 million years, Spicomellus represents the earliest named ankylosaur on record.[2][4]

Quick Facts

Species
afer

Facts from the source article.

Biology and range

This formation represents a shallow marine depositional environment with episodic marine incursions.[5][6] Fused tail vertebrae suggest Spicomellus possessed a tail weapon, the oldest known within Ankylosauria.[7][2] The most complete large spike from this specimen reaches a length of 87 cm.[8][2] It is possible that the spikes evolved to serve both defensive and display functions.[7][2]

What the specialist sources record

The Natural History Museum account notes that the spikes made it difficult to determine where muscles attached, leaving uncertainty about how Spicomellus moved.[2] The same source states that the armour was energetically expensive to produce and likely limited movement.[2] The 2021 description by Maidment et al. considered whether the holotype rib could be part of a fish jaw, but found no evidence of orthodentine to support that classification.[3] GBIF records seven occurrence records for Spicomellus afer as of October 2026.[9]

The GBIF Backbone Taxonomy lists the species authority as Maidment, Strachan, Ouarhache, Scheyer, Brown, Fernandez, Johanson, Raven & Barrett, 2021.[9] A plywood-like arrangement of structural fibers is present in the osteoderms, a feature found in ankylosaurs but absent in other thyreophorans.[3]

References

  1. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Maidment, "Bizarre dermal armour suggests the first African ankylosaur", Nature Ecology & Evolution, 2021-09-23, p. 1576–1581; Davis, "New species of dinosaur had armour unlike anything seen before", Natural History Museum, September 23, 2021 (we also read that source) en.wikipedia.org
  2. Ashworth, ""Bizarre" armoured dinosaur Spicomellus afer rewrites ankylosaur evolution", Natural History Museum. facts only, no text reused. nhm.ac.uk
  3. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Maidment, "Bizarre dermal armour suggests the first African ankylosaur", Nature Ecology & Evolution, 2021-09-23, p. 1576–1581 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Maidment, "Bizarre dermal armour suggests the first African ankylosaur", Nature Ecology & Evolution, 2021-09-23, p. 1576–1581; Clark, "A thyreophoran dinosaur from the Early Bajocian (Middle Jurassic) of the Isle of Skye, Scotland", Scottish Journal of Geology, 2001, p. 19–26 (original not read by us) en.wikipedia.org
  5. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Maidment, "North Africa's first stegosaur: Implications for Gondwanan thyreophoran dinosaur diversity", Gondwana Research, 2020, p. 82–97 (original not read by us) en.wikipedia.org
  6. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Khaffou, "Bajocian–Bathonian dinoflagellate cyst assemblages from the Middle Atlas, Morocco: Palynostratigraphic and paleoenvironmental implications", Review of Palaeobotany and Palynology, 2023 (original not read by us) en.wikipedia.org
  7. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Ashworth, ""Bizarre" armoured dinosaur Spicomellus afer rewrites ankylosaur evolution", Natural History Museum (we also read that source) en.wikipedia.org
  8. Wikipedia, "Spicomellus" (CC BY-SA 4.0), which cites: Maidment, "Extreme armour in the world's oldest ankylosaur", Nature, 2025-08-27, p. 1–6 (original not read by us) en.wikipedia.org
  9. GBIF Backbone Taxonomy and occurrence index, Spicomellus afer (taxon key 11374250). CC BY 4.0 (backbone); counts are facts. gbif.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Spicomellus (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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