Haimirichia: a Cretaceous shark with an unusually broad head

Haimirichia amonensis was a Cretaceous lamniform shark first recognized from isolated teeth. An articulated anterior skeleton from Agoult, Morocco, preserved its broad head, short flattened snout, jaws and sensory structures. The back half of that specimen is absent; the whole animal on the cover is an artistic reconstruction.

Quick facts

From Texas tooth to Moroccan skeleton

Cappetta and Case named Odontaspis amonensis in 1975 from a lateral tooth, UM ACA 3, in the late Cenomanian Woodbine Formation near the former Amon Carter Airfield in Texas. Later authors moved similar teeth among lamniform genera because a single crown had limited anatomical context.

Vullo, Guinot and Barbe described the articulated Agoult specimen in 2016. Its preserved dentition links it to amonensis, while skull and vertebral characters justified the new genus Haimirichia and family Haimirichiidae. A loose tooth is also less informative than associated anatomy in Cretalamna.

What survived at Agoult

The slab and counterslab of UM AGT 1 preserve rostral cartilages, nasal capsules, orbits, tooth rows, gill arches, anterior vertebrae and a pectoral fin. The preserved distance from snout tip to the rear of that fin is about 26 cm. This is the surviving front portion, not the shark's total length.

Agoult's laminated marine limestones belong to the lower Akrabou Formation and are dated to the late Cenomanian, possibly extending into the earliest Turonian. The authors judged that the rear of the carcass was already gone before burial. Its absence was not simply excavation damage.

An uncommon head shape

The head is longer than broad, but the cranium itself is broader than long. The short rostrum has a flattened, bell-like outline and a divided rostral node. The connected tooth rows show how anterior and lateral teeth differed; a detached crown could not reveal that positional sequence.

The fossil preserves cartilage rather than the exact contour of all the living soft tissues. The head illustration highlights the documented broad shape, while skin colour and some surface detail are interpretive.

Skin and electroreception

A separate 2015 study described ampullary structures embedded among specialized denticles on the snout. Their preservation gives rare anatomical evidence for a sensory system in an extinct shark. A proposed role in detecting prey is a functional inference by comparison with living sharks; no prey remains or hunting behavior are documented in this specimen.

Body size and reconstruction

The 2016 authors estimated approximately 1–1.2 m in total length using preserved vertebrae and a comparative model of the absent tail. The estimate is conditional on body proportions. The fossil directly establishes the anterior skeleton, teeth and some skin structures; the complete fin and tail arrangement shown in art is reconstructed.