Nursalia fenestrata n. sp. (Actinopterygii: Pycnodontiformes) dal Turoniano inferiore della Formazione di Akrabou, Marocco sudorientale

Abstract

It
L'autore descrive una nuova specie di picnodonte, Nursallia fenestrata n. sp., proveniente dalla Formazione di Akrabou, datata al Turoniano inferiore, affiorante nell'Alto Atlante marocchino. La nuova specie è un picnodonte di media taglia, caratterizzato dalla presenza: (i) di denti vomerini con corona a contorno circolare con incisura mediana, (ii) di un'ampia finestra temporale, (iii) di articolazioni intervertebrali estremamente complesse per la presenza di tre coppie (anteriori e posteriori) di zigoapofisi su ciascun arcocentro, sia ventrale che dorsale, (iv) di scaglie a barra estese esclusivamente nella regione dorsale, che non oltrepassano mai ventralmente la colonna vertebrale.
En
The author describes the new species of pycnodont, Nursallia fenestrata n. sp., from the Akrabou Formation, dated to the lower Turonian (Late Cretaceous), outcropping in the Moroccan High Atlas Mountains. The new species is a medium-sized pycnodont, characterized by the presence of the following unique combination of the anatomical traits: (i) vomerine teeth with crown with a circular outline and a median notch, (ii) large, well-developed temporal fenestra, (iii) extremely complex intervertebral joints, due to the presence of three pairs (anterior and posterior) of zygoapophyses on each both ventral and dorsal arcocentra, (iv) bar-scales extending exclusively in the dorsal region, never ventrally beyond the vertebral column. The new species has some highly developed characteristics typical of the Nursalliini tribe, such as the complexity of the intervertebral joints. In fact, in Nursallia fenestrata n. sp. the articulations between adjacent arcocentra are hyper-complex throughout the spine. On the other hand, the new species Nursallia fenestrata n. sp. demonstrates that it possesses skeletal characteristics hitherto never found within the Nursalliini tribe, as is the case with the parietal window. Finally, the new species represents the first report of a skeletal remains – moreover in a very peculiar state of conservation (in a three-dimensional calcareous nodule) – of a pycnodon within the Akrabou Formation, dated to the Lower Turonian, outcropping in the Moroccan High Atlas.