Alcione: an unusual small nyctosaurid from Morocco

Alcione elainus was a small nyctosaurid pterosaur from the phosphate deposits of Morocco, less than a million years before the end of the Cretaceous. Its fossils include several individuals, though the bones are disarticulated and do not make one complete skeleton. The unusually short, robust wing bones distinguish it from other nyctosaurids and have prompted debate about its flight and possible use of the water surface. The anatomy is informative; a diving lifestyle is not directly proven. Alcione belongs in the pterosaur catalogue beside the much larger Moroccan nyctosaurid Barbaridactylus.

Quick facts

A small pterosaur from Morocco's last Cretaceous sea

Nicholas Longrich, David Martill and Brian Andres named Alcione elainus in 2018 from fossils in the upper Maastrichtian phosphate series of the Ouled Abdoun Basin near Khouribga, Morocco. The genus name comes from Alcyone of Greek myth, a figure associated with the sea. The type specimen, FSAC-OB 2, includes a humerus, elements of the shoulder girdle, sternum and femur.

Other material assigned to the species includes a lower jaw, parts of the wing and isolated bones from several individuals. These specimens were not found as one articulated body. Researchers compared anatomical details and proportions across the collection to decide which bones belonged to the same taxon. The fossils therefore provide a wider sample of anatomy than one isolated bone, while retaining uncertainty about how each part fits into a single complete skeleton.

The phosphate deposits formed in a shallow marine setting along the north-western edge of Africa. They contain pterosaur bones alongside fish, sharks, marine reptiles and birds. This diverse record helps reconstruct the regional fauna, but it does not mean every taxon lived in the same place at the same time or used the same prey.

The unusual wing proportions

The humerus of Alcione is short and stout, with a greatly expanded upper end and a distinctive axe-shaped deltopectoral crest. The forearm, fourth metacarpal and femur are also comparatively short and robust. The pattern is not simply a consequence of being small: the relative proportions differ from those of other nyctosaurids.

Authors estimated a wingspan of about two metres, substantially less than that of Barbaridactylus, which lived in the same broad Moroccan region. The number is reconstructed from incomplete remains and should be treated as approximate. It describes the scale of the known animal, not an exact measurement of a complete wing.

The lower jaw is toothless and elongated. Its front is narrow, while the branches diverge behind the fused symphysis, producing an outline like a Y when viewed from below. A keratinous beak would have covered the bone in life, but the covering itself is not preserved. Because much of the skull is missing, no large crest like the branched structure of some Nyctosaurus species can be confidently attributed to Alcione.

Did Alcione dive?

The short, robust wing has been compared with the wings of some modern birds that use rapid flapping or dive into water. This prompted the suggestion that Alcione may have launched from the sea surface or plunged toward prey. Such a scenario is possible, but the outline of a wing alone cannot demonstrate underwater movement.

A strong test would require several independent features to agree: bone density, joint surfaces, muscle attachment areas, shoulder mechanics and the proportions of the complete body. The available fossil sample does not preserve all of those parts. Similar proportions can also arise from different flight demands. A bird analogy can generate a hypothesis, but it cannot substitute for the missing pterosaur anatomy.

The toothless beak is compatible with taking small prey near the water, yet no stomach contents or prey are associated with the fossils. The safest description is a small coastal or marine-flying nyctosaurid with an unusual wing. Whether it routinely dived, skimmed the surface or fed in another way remains unresolved.

Several species in a single rich fauna

The same Moroccan phosphate assemblage has yielded at least seven pterosaur species from three families. Alcione and Barbaridactylus represent differently sized nyctosaurids, while Phosphatodraco was a long-necked azhdarchid. This variety shows that pterosaurs were not represented only by one type of giant flyer in the region shortly before the end-Cretaceous extinction.

A particularly diverse locality changes how scientists think about the final chapter of pterosaur evolution, but one place is not a global census. The preservation of phosphate deposits and the intensity of collecting affect which animals are known. It remains uncertain how common each form was elsewhere or how the final extinction unfolded among different lineages.

The fossils establish a distinct, small-bodied nyctosaurid with compact limb proportions and a toothless lower jaw. They do not establish a full skull, a large crest, an exact flight performance or a specialised diving behaviour. Keeping those boundaries visible makes the unusual anatomy more interesting, not less.