A new genus and species of owl that lived 55 million years ago (Eocene epoch) has been identified from a partial skeleton discovered in Wyoming, the United States. The discovery is reported in a paper in the Journal of Vertebrate Paleontology.
The 55-million-year-old skeleton of Primoptynx poliotauros. Image credit: Senckenberg Research Institute / Tränkner.
Named Primoptynx poliotauros, the ancient owl species was about 60 cm (23.six inches) tall.
It belongs to a group of owls closely associated to the extinct family members Protostrigidae.
“The fossil owl was about the size of a modern snowy owl (Bubo scandiacus). However, it is clearly distinguished from all extant species by the different size of its talons,” mentioned lead author Dr. Gerald Mayr, an ornithologist in the Senckenberg Research Institute and Natural History Museum Frankfurt.
“While in present-day owls the talons on all toes are approximately the same size, Primoptynx poliotauros has noticeably enlarged talons on its hind toe and second toe.”
Dr. Mayr and colleagues hypothesize that Primoptynx poliotauros utilized its feet to dispatch prey things in a hawk-like manner, whereas living owls kill prey with their beak.
“Owls today have four toes with claws of equal size to catch relatively small preys and kill them with the beak,” mentioned co-author Dr. Thierry Smith, a paleontologist at the Royal Belgian Institute of Natural Sciences.
“Primoptynx poliotauros has a longer first and second toe, as seen in hawks and other members of the family Accipitridae.”
“Those more developed toes are used to pin down prey, which are punctured by the talons. So it was an owl that hunted like a hawk on medium-sized mammals.”
“The lifestyle of this extinct owl clearly differed from that of its modern relatives,” Dr. Mayr added.
The partial skeleton of Primoptynx poliotauros was discovered by U.S. paleontologists at Bighorn Basin in Wyoming about 30 years ago.
The fossil shows that throughout the Early Eocene there have been currently several species of owls, of various sizes, which occupied various ecological niches.
“The success of the owls runs parallel to that of the mammals, which became very diverse after the fifth mass extinction, which wiped out the dinosaurs,” the researchers mentioned.
“The later extinction of Primoptynx poliotauros and other proto-owls may have been due to the emergence of daytime birds of prey in the Late Eocene.”
“It is not clear why owls changed their hunting technique in the course of their evolution,” Dr. Mayr mentioned.
“However, we assume that it may be related to the spread of diurnal birds of prey in the Late Eocene and Early Oligocene, approximately 34 million years ago.”
“Competition for prey with diurnal birds of prey may have triggered feeding specializations in owls, possibly also leading to these charismatic birds’ nocturnal habits.”
The discovery of Primoptynx poliotauros also revealed a higher level of diversity amongst the owls in the Early Eocene of North America: from the modest species Eostrix gulottai, measuring a mere 12 cm (four.7 inches), to the newly-found big species.
Gerald Mayr et al. Skeleton of a new owl from the early Eocene of North America (Aves, Strigiformes) with an accipitrid-like foot morphology. Journal of Vertebrate Paleontology, published on line July 28, 2020 doi: 10.1080/02724634.2020.1769116