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''Ypresiglaux'' (meaning " Ypresian owl") is an extinct genus of
''Ypresiglaux'' was described in 2022 by German paleontologist Gerald Mayr and British zoologist Andrew C. Kitchener. The generic name, "''Ypresiglaux''", combines a reference to the Ypresian-dated type locality with the Greek word "glaux," meaning "owl". The type species, ''Y. michaeldanielsi'', was described on the basis of a partial skeleton collected in 1992. This specimen, NMS.Z.2021.40.26, which includes the mandible, vertebrae, pectoral girdle, wing bones, and a partial right leg, was designated as the holotype. NMS.Z.2021.40.27, an additional specimen collected in 1982, consists of the distal portion of the right femur, distal half of the right
strigiform
Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers ...
bird from the Early Eocene
In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between , is preceded by the Thanetian Age (part of the Paleocene) and is followed by the Eocene Lutetian Age. The Ypresian i ...
London Clay Formation
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from th ...
of Essex, United Kingdom and Nanjemoy Formation
The Nanjemoy Formation is a geologic formation pertaining to both the Wilcox Group and the Pamunkey Group of the eastern United States, stretching across the states of Virginia, Maryland, and District of Columbia. The formation crops out east of ...
of Virginia, United States. The genus contains two species: ''Y. michaeldanielsi'', known from a partial skeleton, and ''Y. gulottai'', known from a distal tarsometatarsus.
Discovery and naming
''Ypresiglaux'' was described in 2022 by German paleontologist Gerald Mayr and British zoologist Andrew C. Kitchener. The generic name, "''Ypresiglaux''", combines a reference to the Ypresian-dated type locality with the Greek word "glaux," meaning "owl". The type species, ''Y. michaeldanielsi'', was described on the basis of a partial skeleton collected in 1992. This specimen, NMS.Z.2021.40.26, which includes the mandible, vertebrae, pectoral girdle, wing bones, and a partial right leg, was designated as the holotype. NMS.Z.2021.40.27, an additional specimen collected in 1982, consists of the distal portion of the right femur, distal half of the right tarsometatarsus
The tarsometatarsus is a bone that is only found in the lower leg of birds and some non-avian dinosaurs. It is formed from the fusion of several bones found in other types of animals, and homologous to the mammalian tarsus (ankle bones) and meta ...
, and pedal phalanges
The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones.
...
. It was also referred to ''Y. michaeldanielsi''. These fossils were discovered by Michael Daniels in layers of the London Clay Formation
The London Clay Formation is a marine geological formation of Ypresian (early Eocene Epoch, c. 56–49 million years ago) age which crops out in the southeast of England. The London Clay is well known for its fossil content. The fossils from th ...
(Walton Member), dated to the early Ypresian, which is located near Walton-on-the-Naze in Essex, England. The specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
, "''michaeldanielsi''", honors Michael Daniels. ''Y. michaeldanielsi'' represents one of the most completely-known Palaeogene owls.
Additional fossil material, consisting of a partial right femur, partial right tarsometatarsus, and pedal phalanges (specimen NMS.Z.2021.40.27) was also collected from the Walton Member
of the London Clay Formation. Since the fossil material is slightly larger than overlapping bones of ''Y. michaeldanielsi'', it is possible that it represents a female specimen of the latter, since sexual dimorphism has been consistently observed in owls. Some important differences between the bones suggest that they may represent a distinct species. However, due to the lack of morphological differences, the specimen could not be confidently placed beyond "''Ypresiglaux'' sp."
In 2016, Gerald Mayr described a distal right tarsometatarsus as belonging to a new species of the extinct owl genus '' Eostrix'', ''E. gulottai''. The holotype specimen, SMF Av 627, was discovered in layers of the Eocene (Ypresian)-dated Nanjemoy Formation
The Nanjemoy Formation is a geologic formation pertaining to both the Wilcox Group and the Pamunkey Group of the eastern United States, stretching across the states of Virginia, Maryland, and District of Columbia. The formation crops out east of ...
(Potapaco Member) of Stafford County, Virginia, USA. In 2022, Mayr and Kitchener moved '' 'Eostrix' gulottai'' to the new genus ''Ypresiglaux'' as the new combination, ''Y. gulottai''. The specific name honors Marco Gulotta, the discoverer of the specimen.
Description
''Ypresiglaux'' was a very small owl. ''Y. michaeldanielsi'' was comparable in size to theEurasian Pygmy Owl
The Eurasian pygmy owl (''Glaucidium passerinum'') is the smallest owl in Europe. It is a dark reddish to greyish-brown, with spotted sides and half of a white ring around the back of the neck. This species is found in the boreal forests of North ...
, which has a body mass of 50–77 grams. ''Y. gulottai'' was even smaller, and represents the smallest known owl (extinct or extant). It is suggested that it likely had a diet comparable to the similarly-sized extant long-whiskered owlet
The long-whiskered owlet (''Xenoglaux loweryi'') is a tiny owl that is endemic to a small area in the Andean mountains in Amazonas and San Martín in northern Peru. It is restricted to cloud forests with dense undergrowth and epiphytes at about ...
and elf owl, which primarily eat arthropods
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
.
It is likely that ''Ypresiglaux'' did not have the same degree of head rotational mobility as extant owls because of differences in the atlas and axis. Mayr and Kitchener (2022) further suggest that ''Ypresiglaux'' occupied a diurnal niche, contrary to extant owls, which are often nocturnal
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
. Preserved fossilized toe pad integument was observed on a piece of matrix
Matrix most commonly refers to:
* ''The Matrix'' (franchise), an American media franchise
** ''The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
collected with a pedal phalanx. A similar instance was seen in the holotype of the contemporary ''Lutavis
''Lutavis'' (meaning "clay bird") is an extinct genus of potentially afroavian bird from the Early Eocene London Clay Formation of Essex, United Kingdom. The genus contains a single species, ''L. platypelvis'', known from a partial skeleton.
...
''.
Classification
In their phylogenetic analyses, Mayr & Kitchener (2022) recovered ''Ypresiglaux'' in various positions within the Strigiformes. They stated that the discovery of additional fossil material could provide more insight into the exact phylogenetic relationships of ''Ypresiglaux''. The cladogram below displays the results of two different phylogenetic analyses. Topology 1: Strict consensus tree Topology 2: 50% majority-rule consensus treeSee also
*Paleobiota of the London Clay
A list of prehistoric and extant species whose fossils have been found in the London Clay, which underlies large areas of southeast England.
Plant fossils, especially seeds and fruits, are found in abundance and have been collected from the Lond ...
References
{{Taxonbar, from1=Q113656843, from2=Q113784812, from3=Q113799510 Owls Eocene birds of North America Extinct birds of North America Eocene birds of Europe Extinct birds of Europe Prehistoric bird genera Birds described in 2022 Fossil taxa described in 2022