Anurognathidae

Anurognathids Temporal range: Middle Jurassic - Early Cretaceous, 165–122.1 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Life restoration of Anurognathus ammoni
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Order:	†Pterosauria
Clade:	†Caelidracones
Family:	†Anurognathidae Nopcsa, 1928
Type species
†Anurognathus ammoni , 1923
Subgroups
†Daohugoupterus? †Mesadactylus? †? †Anurognathinae †Anurognathus †Jeholopterus †Vesperopterylus †Luopterus †Dendrorhynchoides †Batrachognathinae †Batrachognathus †Cascocauda †Sinomacrops

Anurognathidae is a family of small pterosaurs, with short or absent tails, that lived in Europe, Asia, and possibly North America during the Jurassic and Cretaceous periods. Five genera are known: Anurognathus, from the Late Jurassic of Germany; Jeholopterus, from the Middle to Late Jurassic of China;^[1] Dendrorhynchoides, from the Middle Jurassic^[2] of China; Batrachognathus, from the Late Jurassic of Kazakhstan; and Vesperopterylus, from the Early Cretaceous of China.^[3] Bennett (2007) claimed that the holotype of Mesadactylus, BYU 2024, a synsacrum, belonged to an anurognathid.^[4] Mesadactylus is from the Late Jurassic Morrison Formation of the United States. Indeterminate anurognathid remains have also been reported from the Middle Jurassic Bakhar Svita of Mongolia^[5][6] and the Early Cretaceous of North Korea.^[7]

Classification[]

Anurognathid skeletons to scale

A family Anurognathidae was named in 1928 by Franz Nopcsa von Felső-Szilvás (as the subfamily Anurognathinae) with Anurognathus as the type genus. The family name Anurognathidae was first used by Oskar Kuhn in 1967. Both Alexander Kellner and in 2003 defined the group as a node clade: the last common ancestor of Anurognathus and Batrachognathus and all its descendants.

The phylogeny of the Anurognathidae is uncertain. Some analyses, as those of Kellner, place them very basal in the pterosaur tree. However, they do have some characteristics in common with the derived Pterodactyloidea, such as the short and fused tail bones. In 2010 an analysis by indicated the Anurognathidae and the Pterodactyloidea were sister taxa. This conforms better to the fossil record because no early anurognathids are known and would require a ghost lineage of over sixty million years.^[8]In 2022 the discovery of Cascocauda would confirm its existence.^[9]

Lifestyle[]

Anurognathids are often believed to have been nocturnal or crepuscular akin to bats. The fact that many anurognathids have large eye-sockets supports the theory of living in darkness. Anurognathid teeth suggest they were insectivorous, though some may have had more prey-choices, such as Jeholopterus who is also believed to have been a fish-eater. At least some, such as Vesperopterylus, were arboreal, with claws suited for gripping tree branches.^[3]

Feathers[]

A study of pair of anurognathid specimens purported to show that that pterosaur pycnofibers were actually proto-feathers. These include at least four types, ranging from simple monofilaments to down-like structures and branched whiskers.^[10] However, these were later disputed, with other authors suggesting that the supposed branching actually were taphonomic artefacts, stating that "When bunched up, or partially decomposed and unravelled, structural fibres (aktinofibrils) in the wing membranes of pterosaurs exhibit a variety of seemingly branched morphologies including brush-like and tuft-like structures".^[11]

Notes[]