Eoalulavis

Eoalulavis (from the Ancient Greek: Éōs, "dawn"; alula, "bastard wing"; avis, "bird") is a monotypic genus of enantiornithean bird that lived during the Barremian, in the Lower Cretaceous around 125 million years ago. The only known species is Eoalulavis hoyasi. Its remains came from the Konservat-Lagerstätte of Las Hoyas, Cuenca, Spain. The holotype (LH13500), housed in the collection of es, consists on both slab and counterslab preserving mainly the thoracic region, part of the neck and both almost complete forelimbs of an adult specimen. It also preserves remains of the body, primary, secondary feathers and a bastard wing which have been covered by layers of limonite as a result of the fossilization process. The preservation is consistent with the taphonomic processes associated with obruption, stagnation and the action of microbial mats in the locality that have yielded a wide variety of examples of soft-tissue preservation (e.g., connective tissues in fishes and theropods or insect wings). Most of the osteological features of the holotype became apparent only after its acid preparation and transference to a resin cast. According to its initial description, E. hoyasi was roughly the size of a european goldfinch (Carduelis carduelis), with the bony elements of its wings approximately 17 centimeters (7 inches) in length. Later studies estimated that it had a weight of approximately 45 grams (1.6 ounces) and total wingspan (including feathers) of about 26 centimeters (10 inches), giving it proportions similar to those of a common kingfisher (Alcedo atthis). One of the most unusual features of this genus lies in the shape of its bony sternum (breastplate). While most early birds had wide sternums, Eoalulavis had a very thin one, with an expanded front end tapering to a point as well as a rear tip with outward-pointing extensions. This form has been described as "spear-shaped" or "fish-shaped" by some. The morphology of the forelimb in Eoalulavis is remarkably primitive compared with that of other genera of enantiornithean birds.