Article: Loriolella, a key taxon for understanding the early evolution of irregular echinoids

Loriolella Fucini is an enigmatic and poorly understood Early Jurassic sea-urchin that has been interpreted both as a regular and an irregular echinoid. The discovery of new and well-preserved material of the type species L. ludovicii (Meneghini) from the Upper Pliensbachian (Lower Jurassic) of Lombardy, Italy, has clarified the morphology of this genus for the first time. Loriolella resembles regular echinoids in having a large (almost certainly monocyclic) apical disc enclosing the periproct, and large primary interambulacral tubercles and spines. However, its peristome is extremely small with only vestigial buccal notches and auricles, and the ambulacra expand adorally forming cassiduloid-like phyllodes. Cladistic analysis suggests that Loriolella is the earliest known microstomatid irregular echinoid. Its unique mixture of primitive and derived characters is important for interpreting the initial steps by which irregular echinoids arose from diadematoid-like regular ancestors.