Messelasturidae is an extinct family of birds known from the Eocene of North America and Europe. Their morphology is a Mosaic evolution that in some aspects are very similar to modern hawks and falcons, but in others are more similar to . Initially interpreted as stem-owls, more recent studies have suggested a closer relationship to parrots and . Their ecology is enigmatic.
Description
On the skull, Messelasturidae possessed a
raptorial beak and a large
Brow ridge process.
On the feet, messelasturids lacked an ossified supratendineal bridge on the distal tibiotarsus.
They were likely ground dwelling carnivores. They existed at an age range of 61.7 to 40.4 Ma.
Tynskya is characterized by a distinctive morphology of the tarsometatarsus.
Discovery and classification
Messelastur was originally described in 1994 from two skulls with associated vertebrae, found in the
Eocene aged
Messel pit, Germany.
[Peters, D.S. (1994) Messelastur gratulator n. gen. n. spec., ein Greifvogel as der Grube Messel (Aves: Accipitridae). Courier Forschungsinstitut Senckenberg, 170:3-9] Tynskya was described from specimens found in the Eocene aged Green River Formation in the western United States by
Gerald Mayr in 2000, with indeterminate similar remains also being noted from the equivalently aged
London Clay of southern England.
In 2005, a more complete skeleton of
Messelastur was described, and it and
Tynskya were placed into their own family Messelasturidae by Mayr, as the sister group of
Owl or possibly
Falconiformes.
An additional specimen of
Messelastur from Messel pit was described in 2011 by Mayr, finding that Messelasturidae was closely related to the extinct family
Halcyornithidae, and both were likely
to
Psittaciformes.
A study in 2021 described a new species of
Tynskya,
T. waltonensis from the London Clay. A phylogenetic analysis constrained to molecular data conducted in the study found messelasturids closely related to
Psittacopasserae, the clade containing
Passeriformes and
Psittaciformes, but a sister group relationship with Halcyornithidae was not recovered.
Ecology
Due to the mosaic nature of the morphology of messelasturids, their ecology is difficult to assess. It is likely they had a specialised feeding ecology. It is unlikely that they regularly searched the ground for food or engaged in hawking via sallying flights from perches. It is possible that they had a raptorial ecology, and hard shelled invertebrates have also been suggested as a food source, but other items like fruit and seeds cannot be ruled out.
Distribution
Fossils of
Messelastur are known from Germany (Messel).
Tynskya remains have been found in the US (Green River Formation), and in the UK (
London Clay), illustrating the resemblance between the early Eocene birds of North America and Europe.
Indeterminate messelasturid remains have also been reported from the early Eocene Nanjemoy Formation of Virginia in the United States.
An indeterminate bird from the
Paleocene aged
Menat Formation maar deposit in France bears similarities to both Messelasturidae and Halcyornithidae.
