Monofenestrata is a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

pterosaur Pterosaurs are an extinct clade of flying reptiles in the order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earli ...

s. It includes the pterosaurs in which the nasal and antorbital

fenestra A fenestra (fenestration; : fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biology, biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomy, ...

(openings/holes) in the skull are merged into a single fenestra. The clade includes the pterodactyloids and their close relatives.

Classification

The

Monofenestrata was in 2010 defined as the group consisting of ''

Pterodactylus ''Pterodactylus'' (from ) is a genus of extinct pterosaurs. It is thought to contain only a single species, ''Pterodactylus antiquus'', which was the first pterosaur to be named and identified as a flying reptile and one of the first prehis ...

'' and all species sharing with ''Pterodactylus'' the

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...

of an external nostril confluent with the

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with Archosauriformes, archosauriforms, first appearing during the Triassic Period. Among Extant ...

, the major skull opening on the side of the snout. The name is derived from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''monos'', "single", and

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''fenestra'', "window". The concept was inspired by the discovery of '' Darwinopterus'', a species combining a pterodactyloid-type skull with a more basal build of the remainder of the body. The Darwinoptera, a primitive subgroup of monofenestratans showing this transitional anatomy, was also named for ''Darwinopterus'' and defined as all descendants of its common ancestor with '' Pterorhynchus''. Below is a

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

showing the results of a

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

analysis presented by Andres, Clark & Xu, 2014. This study found the two traditional groupings of ctenochasmatoids and kin as an early branching group (represented as the group Archaeopterodactyloidea), with all other pterodactyloids grouped into the Eupterodactyloidea. Contrastingly, a 2024 paper by David Hone and colleagues describing the transitional taxon '' Skiphosoura'' found primitive monofenestratans to represent an

evolutionary grade A grade is a taxon united by a level of morphological or physiological complexity. The term was coined by British biologist Julian Huxley, to contrast with clade, a strictly phylogenetic unit. Phylogenetics The concept of evolutionary grades ...

leading towards Pterodactyloidea, rather than a distinct darwinopteran or wukongopterid grouping. A cladogram of their results is shown below.

Distribution

The earliest known monofenestratan fossils have been found in the Stonesfield Slate formation of the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

, which dates to the

Bathonian In the geologic timescale the Bathonian is an age (geology), age and stage (stratigraphy), stage of the Middle Jurassic. It lasted from approximately 168.2 ±1.2 annum, Ma to around 165.3 ±1.1 Ma (million years ago). The Bathonian Age succeeds ...

stage of the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

, dated to about 166 million years ago. Identified elements include cervical vertebrae, fourth metacarpals and a possible pterodactyloid synsacrum.Michael O’Sullivan; David M. Martill (2018). "Pterosauria of the Great Oolite Group (Bathonian, Middle Jurassic) of Oxfordshire and Gloucestershire, England". Acta Palaeontologica Polonica. Online edition. . An earlier undescribed taxon along with the coeval and corregional '' Allkaruen'' may also belong to the group, both reported from Middle

Toarcian The Toarcian is, in the International Commission on Stratigraphy, ICS' geologic timescale, an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic. It spans the time between 184.2 Megaannum, Ma (million ...

layers of the Cañadón Asfalto Formation of Argentina.

References

{{Taxonbar, from=Q6901581 Callovian first appearances Maastrichtian extinctions