Iberomesornis
Encyclopedia
Iberomesornis is a monotypic
genus
of enantiornithine
bird
of the Cretaceous
of Spain
.
In 1985 the fossil
of Iberomesornis was discovered by Armando Díaz Romeral in the Early Cretaceous
Calizas de La Huérguina Formation at Las Hoyas
, Cuenca Province, east central Spain, which dates to the late Barremian
, roughly 125 million years ago. The find was first reported in 1988. In 1992 the type species
Iberomesornis romerali was named and described by José Luis Sanz and José Fernando Bonaparte. The generic name is derived from Iberia
and Greek μέσος, mesos, "middle", en ὄρνις, ornis, "bird", in reference to the intermediate status between the most basal and the modern birds. The specific name honours Romeral.
The holotype
specimen, LH-22, part of the Las Hoyas Collection, consists of a compressed articulated partial skeleton of an adult individual lacking the skull, the anterior neck and most of the hands. A second specimen, LH-8200, was referred to a Iberomesornis sp. in 1994, consisting of the left foot of an individual similar in size to the holotype. After further preparation of the fossil, the species was redescribed by Paul Sereno
in 2000.
Iberomesornis was quite small, no bigger than a large modern sparrow
. On the assumption it had relatively short wings, the wingspan was about twenty centimetres; its weight has been estimated at fifteen to twenty grammes. It bore a single claw on each wing. The preserved axial column length is eighty-seven millimetres. Its ribcage was not strengthened by ossified uncinate process
es but cartilaginous processes were likely present.
The Las Hoyas Unit 3 site was once a forest surrounding a lake; the climate was warm with a distinct dry season. Since the skull is not known, the diet of Iberomesornis remains a subject of guesswork. It perhaps hunted insects and other small animals, plucking them out of the air or from the ground. It may have preferred to live near to lakes, catching insects from the water's surface. When resting, it used its strong, clawed feet to perch on branches; the toes are long with curved claws and a low and long hallux
improved the grasping ability.
. The basal characteristic of a long tail had been lost and the coracoid was longer. The vertebrate column of Iberomesornis ended in a pygostyle
: a splint of bone made of fused tail vertebrae that supports the tail feathers. The shorter tail and the higher position of the shoulder indicated by the strut-like coracoid — allowing for a greater wing amplitude — improved manoeuvrability, turning and swooping at speed. Low speed flying might have been impaired by the lack of a bony keel on the sternum as attachment for the flight muscles; it is uncertain whether a true foramen triosseum was present, through which a tendon could elevate and supinate
the wing.
In 1992 Iberomesornis was assigned to the Iberomesornithidae
. At that time it was considered to possibly have been very basal, outside of the clade
Ornithothoraces
, as is reflected by its generic name. However, since the discovery of Iberomesornis, many more bird fossils have come to light in the quarries of Liaoning
province, China. Well preserved specimens of Chinese species such as Sinornis and Confuciusornis
have permitted scientists to better understand the birds' early fossil history. Today, Iberomesornis is seen as positioned within Ornithothoraces, as a basal member of the Enantiornithes
.
series Walking with Dinosaurs
, where they were depicted as having bright blue feathers; the birds of La Hoyas are often reconstructed with an orange or pinkish hue because Eoalulavis
was found with the remains of small crustaceans from which it could have absorbed pigments of such colours.
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of enantiornithine
Enantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
of Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
.
In 1985 the fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
of Iberomesornis was discovered by Armando Díaz Romeral in the Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
Calizas de La Huérguina Formation at Las Hoyas
Las Hoyas
Las Hoyas is a Cretaceous Konservat-Lagerstätten located near the city of Cuenca, Spain.It is dated as Barremian , and is mostly known from its exquisitely preserved dinosaurs, especially enantiornithines.- Taphonomy :...
, Cuenca Province, east central Spain, which dates to the late Barremian
Barremian
The Barremian is an age in the geologic timescale between 130.0 ± 1.5 Ma and 125.0 ± 1.0 Ma). It is a subdivision of the Early Cretaceous epoch...
, roughly 125 million years ago. The find was first reported in 1988. In 1992 the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
Iberomesornis romerali was named and described by José Luis Sanz and José Fernando Bonaparte. The generic name is derived from Iberia
Iberia
The name Iberia refers to three historical regions of the old world:* Iberian Peninsula, in Southwest Europe, location of modern-day Portugal and Spain** Prehistoric Iberia...
and Greek μέσος, mesos, "middle", en ὄρνις, ornis, "bird", in reference to the intermediate status between the most basal and the modern birds. The specific name honours Romeral.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
specimen, LH-22, part of the Las Hoyas Collection, consists of a compressed articulated partial skeleton of an adult individual lacking the skull, the anterior neck and most of the hands. A second specimen, LH-8200, was referred to a Iberomesornis sp. in 1994, consisting of the left foot of an individual similar in size to the holotype. After further preparation of the fossil, the species was redescribed by Paul Sereno
Paul Sereno
Paul Callistus Sereno is an American paleontologist from the University of Chicago who discovered several new dinosaur species on several continents. He has conducted excavations at sites as varied as Inner Mongolia, Argentina, Morocco, and Niger...
in 2000.
Biology and ecology
Sparrow
The sparrows are a family of small passerine birds, Passeridae. They are also known as true sparrows, or Old World sparrows, names also used for a genus of the family, Passer...
. On the assumption it had relatively short wings, the wingspan was about twenty centimetres; its weight has been estimated at fifteen to twenty grammes. It bore a single claw on each wing. The preserved axial column length is eighty-seven millimetres. Its ribcage was not strengthened by ossified uncinate process
Uncinate process
Uncinate process can refer to:* Uncinate process of ethmoid bone* Uncinate process of vertebra - a hook shaped process on the lateral borders of the superior surface of the vertebral bodies of the third to the seventh cervical vertebrae....
es but cartilaginous processes were likely present.
The Las Hoyas Unit 3 site was once a forest surrounding a lake; the climate was warm with a distinct dry season. Since the skull is not known, the diet of Iberomesornis remains a subject of guesswork. It perhaps hunted insects and other small animals, plucking them out of the air or from the ground. It may have preferred to live near to lakes, catching insects from the water's surface. When resting, it used its strong, clawed feet to perch on branches; the toes are long with curved claws and a low and long hallux
Hallux
In tetrapods, the hallux is the innermost toe of the foot. Despite its name it may not be the longest toe on the foot of some individuals...
improved the grasping ability.
Phylogeny
Iberomesornis romerali was more derived physically than ArchaeopteryxArchaeopteryx
Archaeopteryx , sometimes referred to by its German name Urvogel , is a genus of theropod dinosaur that is closely related to birds. The name derives from the Ancient Greek meaning "ancient", and , meaning "feather" or "wing"...
. The basal characteristic of a long tail had been lost and the coracoid was longer. The vertebrate column of Iberomesornis ended in a pygostyle
Pygostyle
Pygostyle refers to a number of the final few caudal vertebrae fused into a single ossification, supporting the tail feathers and musculature. In modern birds, the rectrices attach to these....
: a splint of bone made of fused tail vertebrae that supports the tail feathers. The shorter tail and the higher position of the shoulder indicated by the strut-like coracoid — allowing for a greater wing amplitude — improved manoeuvrability, turning and swooping at speed. Low speed flying might have been impaired by the lack of a bony keel on the sternum as attachment for the flight muscles; it is uncertain whether a true foramen triosseum was present, through which a tendon could elevate and supinate
Supination
Supination is a position of either the forearm or foot; in the forearm when the palm faces anteriorly, or faces up . Supination in the foot occurs when a person appears "bow-legged" with their weight supported primarily on the anterior of their feet.The hand is supine in the anatomical position...
the wing.
In 1992 Iberomesornis was assigned to the Iberomesornithidae
Iberomesornithidae
Iberomesornithidae is an extinct family of enantiornithine birds.*Order Iberomesornithiformes**Family Iberomesornithidae***Enantiornithes gen. et sp. indet. CAGS-IG-07-CM-001***Iberomesornis ***Noguerornis...
. At that time it was considered to possibly have been very basal, outside of the clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
Ornithothoraces
Ornithothoraces
Ornithothoraces is a clade of birds which includes all enantiornithines and modern birds .The name Ornithothoraces means "bird thoraxes". This refers to a modern, highly derived, anatomy of the thorax which gave the ornithothoracines superior flight capability compared to more primitive birds...
, as is reflected by its generic name. However, since the discovery of Iberomesornis, many more bird fossils have come to light in the quarries of Liaoning
Liaoning
' is a province of the People's Republic of China, located in the northeast of the country. Its one-character abbreviation is "辽" , a name taken from the Liao River that flows through the province. "Níng" means "peace"...
province, China. Well preserved specimens of Chinese species such as Sinornis and Confuciusornis
Confuciusornis
Confuciusornis is a genus of primitive crow-sized birds from the Early Cretaceous Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago...
have permitted scientists to better understand the birds' early fossil history. Today, Iberomesornis is seen as positioned within Ornithothoraces, as a basal member of the Enantiornithes
Enantiornithes
Enantiornithes is an extinct group of primitive birds. They were the most abundant and diverse avialans of the Mesozoic. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over 50 species of Enantiornithines have been named, but some...
.
Popular culture
They appeared in the BBCBBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
series Walking with Dinosaurs
Walking with Dinosaurs
Walking with Dinosaurs is a six-part documentary television miniseries that was produced by BBC, narrated by Kenneth Branagh, and first aired in the United Kingdom, in 1999. The series was subsequently aired in North America on the Discovery Channel in 2000, with Branagh's voice replaced with that...
, where they were depicted as having bright blue feathers; the birds of La Hoyas are often reconstructed with an orange or pinkish hue because Eoalulavis
Eoalulavis
Eoalulavis was an enantiornithine bird. It lived during the Aptian in the Early Cretaceous, about 115 mya and is known from fossils found at Las Hoyas, Spain...
was found with the remains of small crustaceans from which it could have absorbed pigments of such colours.