Wyleyia
Encyclopedia
Wyleyia is a prehistoric bird
genus
with a single species
, Wyleyia valdensis, known from the Early Cretaceous
of England
. Even this is only known from a single damaged right humerus
. It has been named to honor J. F. Wyley, who found the specimen in the Weald Clay
deposits of Henfield
in Sussex
(England
). The specific name valdensis means "from the Weald
".
The bone was found in what appears to be a Berriasian
or maybe a Valanginian
deposit, meaning it lived about 142-140 million years ago
Once believed by some to be from a non-avialan
coelurosaur, it is now generally accepted as an early bird
, although its exact systematic
position is unresolved. It has been proposed to be an enantiornithine
or an early neornithine palaeognathe
. Even C.J.O. Harrison
and C.A. Walker, usually quick to assign their species to some group, found it
No new material evidence has been found. A cladistic analysis finds W. valdensis to be possibly a basal enantiornithine of uncertain affinities. What little information can be gleaned from it suggests it was a pygostylia
n - an early bird more advanced than Archaeopteryx
and possibly related to living birds. This supposed clade
may be paraphyletic however. In any case, among the Pygostylia, it most closely resembles the early Enantiornithes and Ornithurae
. It may thus be that Wyleyia represents a bird close to the point in evolution
where the former separated from the lineage leading to modern birds. It does not seem to be particularly close to modern birds, paleognaths or not.
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...
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...
with a single species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, Wyleyia valdensis, known from the Early 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 England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
. Even this is only known from a single damaged right humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. It has been named to honor J. F. Wyley, who found the specimen in the Weald Clay
Weald Clay
Weald Clay is a Lower Cretaceous sedimentary rock underlying areas of South East England. It is part of the Wealden Group of rocks. The clay is named after the Weald, an area of Sussex. It varies from orange and grey in colour and is used in brickmaking....
deposits of Henfield
Henfield
Henfield is a large village and civil parish in the Horsham District of West Sussex, England. It lies south of London, northwest of Brighton, and east northeast of the county town of Chichester at the road junction of the A281 and A2037. The parish has a land area of . In the 2001 census 5,012...
in Sussex
Sussex
Sussex , from the Old English Sūþsēaxe , is an historic county in South East England corresponding roughly in area to the ancient Kingdom of Sussex. It is bounded on the north by Surrey, east by Kent, south by the English Channel, and west by Hampshire, and is divided for local government into West...
(England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
). The specific name valdensis means "from the Weald
Weald
The Weald is the name given to an area in South East England situated between the parallel chalk escarpments of the North and the South Downs. It should be regarded as three separate parts: the sandstone "High Weald" in the centre; the clay "Low Weald" periphery; and the Greensand Ridge which...
".
The bone was found in what appears to be a Berriasian
Berriasian
In the geological timescale, the Berriasian is an age or stage of the Early or Lower Creteceous. It is the oldest or lowest subdivision in the entire Cretaceous. It spanned between 145.5 ± 4.0 Ma and 140.2 ± 3.0 Ma...
or maybe a Valanginian
Valanginian
In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 140.2 ± 3.0 Ma and 136.4 ± 2.0 Ma...
deposit, meaning it lived about 142-140 million years ago
Once believed by some to be from a non-avialan
Avialae
Avialae is a clade of dinosaurs containing their only living representatives, birds , and the most immediate extinct relatives of birds.-Competing definitions:...
coelurosaur, it is now generally accepted as an early 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...
, although its exact systematic
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
position is unresolved. It has been proposed to be an 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...
or an early neornithine palaeognathe
Paleognathae
The Palaeognathae or paleognaths are one of the two living superorders of birds. The other living superorder is Neognathae. Together these two clades form the subclass Neornithes....
. Even C.J.O. Harrison
Colin Harrison (ornithologist)
Colin James Oliver Harrison was an English ornithologist.Harrison was born in London, UK. He got a scholarship to grammar school, and then worked as a librarian and a teacher. He had been interested in birds since childhood, and joined an expedition to study autumn migration in Norway...
and C.A. Walker, usually quick to assign their species to some group, found it
"... advisable to consider the new genus incertae sedisIncertae sedis, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
until further evidence of affinity is forthcoming."
No new material evidence has been found. A cladistic analysis finds W. valdensis to be possibly a basal enantiornithine of uncertain affinities. What little information can be gleaned from it suggests it was a pygostylia
Pygostylia
Pygostylia is a group of birds which includes Confuciusornis and all of the more derived birds; the Ornithothoraces. Chiappe defined the Pygostylia as "the common ancestor of the Confuciusornithidae and Neornithes plus all its descendants". This is a node-based definition.Chiappe united the...
n - an early bird more advanced than Archaeopteryx
Archaeopteryx
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"...
and possibly related to living birds. This supposed 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...
may be paraphyletic however. In any case, among the Pygostylia, it most closely resembles the early Enantiornithes and Ornithurae
Ornithurae
Ornithurae is the name of a natural group which includes all modern birds as well as their extinct relatives with plough-shaped pygostyles, a bone at the end of the tail which allows the tail feathers to fan and retract....
. It may thus be that Wyleyia represents a bird close to the point in evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
where the former separated from the lineage leading to modern birds. It does not seem to be particularly close to modern birds, paleognaths or not.