''Eoalulavis'' (from the Ancient Greek: ''Éōs'', "dawn"; ''alula'', "bastard wing"; ''avis'', "

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

") is a

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

genus of

enantiornithean The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

bird that lived during the

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

, in the

Lower Cretaceous Lower may refer to: *Lower (surname) *Lower Township, New Jersey *Lower Receiver (firearms) *Lower Wick Lower Wick is a small hamlet located in the county of Gloucestershire, England. It is situated about five miles south west of Dursley, eight ...

around 125 million years ago. The only known species is ''Eoalulavis hoyasi''. (1996)
An Early Cretaceous bird from Spain and its implications for the evolution of avian flight
''

Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...

'' 382(6590): 442-445. (HTML abstract) (2002): "The birds from the lower Cretaceous of las hoyas (Province of Cuenca, Spain)", Mesozoic Birds: Above the Heads of the Dinosaurs.University of California Press, Berkeley, , pp. 209-229.

Discovery

Its remains came from the Konservat-Lagerstätte of Las Hoyas, Cuenca,

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

(LH13500), housed in the collection of , 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 Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anima ...

primary Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...

secondary Secondary may refer to: Science and nature * Secondary emission, of particles ** Secondary electrons, electrons generated as ionization products * The secondary winding, or the electrical or electronic circuit connected to the secondary winding i ...

feathers and a bastard wing which have been covered by layers of

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·H2O, although this is not entirely accurate as the ratio of oxide to hydroxid ...

as a result of the

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

ization process. The preservation is consistent with the

taphonomic Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...

processes associated with obruption, stagnation and the action of microbial mats in the locality (1997): "The mineralization of dinosaur soft tissue in the Lower Cretaceous of Las Hoyas, Spain", Journal of the Geological Society, vol. 154, no. 4, pp. 587-588. that have yielded a wide variety of examples of soft-tissue preservation (e.g.,

connective tissue Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...

s in fishes and theropods or insect wings (2010): "A holistic approach to the palaeoecology of Las Hoyas Konservat-Lagerstätte (La Huérguina Formation, Lower Cretaceous, Iberian Ranges, Spain)", ''

Journal of Iberian Geology ''Journal of Iberian Geology'' (formerly ''Cuadernos de Geología Ibérica'') is a triannual peer-reviewed scientific journal published by the Universidad Complutense de Madrid. The journal covers the field of geology and related earth sciences ...

'', vol. 36, no. 2, pp. 297-326.). Most of the osteological features of the

became apparent only after its

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

preparation and transference to a resin cast.

Description

Size

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'').

Characteristics

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

birds. (2011): "Pre-modern birds: avian divergences in the Mesozoic", Living dinosaurs: the evolutionary history of modern birds.Edited by GJ Dyke, and G.Kaiser.John Wiley and Sons Ltd., London, UK, , pp. 39-114. The alular and major digits both bear a large ungual phalanx and the minor one bears two phalanx. Also the alular digit extends until the distal end of the major metacarpal, which is considered a primitive trait within the

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

Enantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

. At the time of its discovery, it was the earliest bird known to possess an alula, a batch of feathers on the alular (first) digit that in

modern birds Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight s ...

can be separately moved to improve stability at low flight speeds. Later, more

specimens were discovered with alula (2000): "A primitive enantiornithine bird and the origin of feathers", Science, vol. 290, no. 5498, pp. 1955-1959. (2005): "Anatomy of the Early Cretaceous bird Eoenantiornis buhleri (Aves: Enantiornithes) from China", Canadian Journal of Earth Sciences, vol. 42, no. 7, pp. 1331-1338. and this fact has consequently strengthen the hypothesis that these animals were able to develop a highly complex and active flight. The wide presence of this trait in both

and

Ornithuromorpha Euornithes (from Greek ' meaning "true birds") is a natural group which includes the most recent common ancestor of all avialans closer to modern birds than to ''Sinornis''. Description Clarke ''et al''. (2006) found that the most primitive know ...

, the

which comprises

along with their

counterparts, suggest that the development of the alula, and the flight capabilities that it implies, occur early in the avian evolution, presumably in the base of

Ornithothoraces Ornithothoraces is a group of avialans that includes all enantiornithes ("opposite birds") and the euornithes ("true birds"), which includes modern birds and their closest ancestors. The name Ornithothoraces means "bird thoraxes". This refers to ...

Paleobiology and Paleoecology

Flight

The presence of alula and a complete set of aerodynamic asymmetric feathers arranged forming a modern wing, (2012): "Primitive Wing Feather Arrangement in ''Archaeopteryx lithographica'' and ''Anchiornis huxleyi''", Current Biology, . indicate well develop flight capabilities, as in many other

taxa. Its hindlimb morphology remain uncertain as no material of this kind referable to the genus has been found to date. A 2018 study analyzed the proportions of ''Eoalulavis'' and ''

Concornis ''Concornis'' is a genus of enantiornithean birds which lived during the early Cretaceous period, in the late Barremian age about 125 million years ago. Its remains are known from the Calizas de La Huérgina Formation at Las Hoyas, Cuenca prov ...

'' to determine the optimal flight pattern for those genera. The study found that they likely engaged in bounding flight, a form of flight popular among modern small and short-winged birds. A bird engaging in bounding flight alternates between upward-thrusting flaps and short dives with folded wings. The study also found that they were capable of continuous flapping flight, but were likely unable to glide due to having a high body mass to wingspan ratio. The study concluded that ''Eolalulavis'', ''Concornis'', and likely many other enantiornitheans alternated between the fast bounding flight and the slower but more efficient flapping flight depending on the circumstances, similar to modern songbirds and woodpeckers.

Diet

The

preserves concentrated remains of crustacean cuticles in the area of the abdomen, interpreted as its last meal. It provided the first direct evidence of feeding behaviour in

and in Mesozoic birds in general, though, since then, more examples of undigested food associated with

enantiornithine The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

specimens have been discovered reporting a wide variety of feeding habits. This fact has been interpreted as evidence of an ecological role in ''Eoalulavis'' similar to that of extant waders; living mainly in the shore seeking for little invertebrates in a similar way of modern

turnstone Turnstones are two bird species that comprise the genus ''Arenaria'' in the family Scolopacidae. They are closely related to calidrid sandpipers and might be considered members of the tribe Calidriini. The genus ''Arenaria'' was introduced by t ...

Environment

The locality of Las Hoyas was in the

a seasonal

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

wetland ecologically dominated by fully aquatic organisms (e.g.: holostean fishes). The avifauna of the locality includes so far two more enantiornithean taxa: the

sparrow Sparrow may refer to: Birds * Old World sparrows, family Passeridae * New World sparrows, family Passerellidae * two species in the Passerine family Estrildidae: ** Java sparrow ** Timor sparrow * Hedge sparrow, also known as the dunnock or hedg ...

-sized ''

Iberomesornis romerali ''Iberomesornis'' ("Spanish intermediate bird") is a monotypic genus of enantiornithine bird of the Cretaceous of Spain. Discovery In 1985 the fossil of ''Iberomesornis'' was discovered by Armando Díaz Romeral in the Early Cretaceous Calizas ...

'' (1988):
Unusual early cretaceous birds from Spain
, Nature, vol. 331, no. 6155, pp. 433-435. and the starling-sized '' Concornis lacustris.'' ''Eoalulavis hoyasi'' is believed to be the most linked to a semi-aquatic environment of the three. (1992):
A new bird from the Early Cretaceous of Las Hoyas, Spain, and the early radiation of bird
s", Palaeontology, vol. 35, no. 4, pp. 829-845.

Classification

The phylogenetic relationships within

are largely unsolved so far whilst several phylogenetic analyses have been performed in the last decades. (2013): "A new enantiornithine from the Yixian Formation with the first recognized avian enamel specialization", Journal of Vertebrate Paleontology, vol. 33, no. 1, pp. 1-12.(2007): Glorified dinosaurs: the origin and early evolution of birds, John Wiley. However, some groups of Enantiornithes seem to have fairly strong statistical support. In the last cladistic analysis ''Eoalulavis'' groups with the Chinese genus '' Liaoningornis'' forming a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

group of derived Enantiornithes. Nevertheless, this concrete grouping has not a high statistical support and the enantiornithean status of ''Liaoningornis'' remains currently controversial. (2002): "A new and primitive enantiornithine bird from the Early Cretaceous of China", Journal of Vertebrate Paleontology, vol. 22, no. 1, pp. 49-57. (2012): "A revised look at ''Liaoningornis longidigitrus'' (Aves)", Vertebrata PalAsiatica, vol. 5, no. 1, pp. 25-37. ''Eoalulavis hoyasi'' presents numerous

synapomorphies In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

that justifies the inclusion of the taxon within Enantiornithes and the less inclusive

Euenantiornithes The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

. (2002): "Skeletal morphology and systematics of the Cretaceous Euenantiornithes (Ornithothoraces: Enantiornithes)", Mesozoic birds: above the heads of dinosaurs, , pp. 240-267. These traits include a groove in the inter-osseous surface of radius or a conspicuous foramen in the dorsal surface of the strut-like

coracoids A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...

References

{{Taxonbar, from=Q5381581 Enantiornitheans Euenantiornitheans Bird genera Cretaceous birds of Europe Cretaceous Spain Fossils of Spain Fossil taxa described in 1996 La Huérguina Formation