The Aspidoceratidae comprise a family of middle and upper Jurassic

Jurassic

The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

 ammonites

Ammonitida

The Ammonitida is an order of more highly evolved ammonoid cephalopods from the Jurassic and Cretaceous time periods, commonly with intricate ammonitic sutures....

 that make up part of the superfamily Perisphinctaceae

Perisphinctaceae

Perisphinctoidea, formerly Perisphinctaceae, is a superfamily of Middle Jurassic to Lower Cretaceous ammonites, commonly with evolute shells with strong ribbing that typically divides about mid flank before crossing the venter....

, characterized by evolute shells, commonly stocky, that tend to develop tubercles.

The Aspidoceratidae are thought to be derived from the Perisphinctidae and have been subdivided into three subfamilies, the Aspidoceratinae

Aspidoceratinae

The Aspidoceratinae is a subfamily in the perisphictacean ammonite family, Aspidoceratidae found world wide in middle and upper Jurassic sediments....

, Peltoceratinae

Peltoceratinae

The Peltoceratinae comprise a subfamily in the Aspidoceratidae, .Genera in the Peltoceratinae have sharply ribbed inner whorls and outer whorls that bear spines or tubercles, or have coarse simple ribs...

, and Simoceratinae

Simoceratinae

The Simoceratinae is a subfamily in the Aspidoceratidae, a family of ammonites in the Perisphinctaceae, that lived during most of the Late Jurassic, especially in the Pacific and Tethyan realms. Early genera more closely resemble Perisphictidae and have constricted apertures...

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References

• Arkell, et al, Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L (Ammonoidea). Geol Soc of America and Univ Kansas Press.