Friday, October 7, 2011

Landbirds (Owl)

Landbirds (Owl)
  • Pterosaur (eg. Pterodactylidae/Dsungaripteroidea)  eg. Nemicolopterus -->
  • Enantiornithes landbird subgroup -->
  • Primitive owls,  (eg. Sophiornithidae?--> 
  • Strigiformes (eg. owls), Caprimulgiformes (eg. nighthawks)


Nemicolopterus also demonstrates clear adaptations of the toes and claws for grasping tree branches. Most pterosaurs are known from marine sediments, meaning that they probably caught fish in the ocean and landed on the adjacent beaches or cliffs. Nemicolopterus, on the other hand, is one of just a few known pterosaurs that lived in the continental interior, and probably hunted insects and roosted in the forest canopy.
Sophiornithidae (literally "Wisdom Birds"), was a family of chicken-sized predatory birds that lived from the Paleocene to the Eocene periods of the Cenozoic, and were found primarily in Europe, and are thought to be primitive owls

This chart shows that owls have their own separate lineage (within the landbird branch) which supports what I have proposed concerning owls:

"I wanted to quickly draw attention to a part of the wing that often gets overlooked…..the hair-like [feather-like?] structures along the trailing edge. Kellner et al. 2009 published a small photograph of this

Combs along the trailing edge of the wing (or turbine when we enter the realm of man-made machines) are known to reduce the noise produced by the animal during flight by collapsing the vortex shed off the wing. There is quite a bit of literature on this subject but its function in biological flight could warrant further attention. Owls are certainly the most famous example where these structures are used to reduce the noise produced by the wings

The examples above show just how similar the trailing edge structures of the wing in Jeholopterus (E) are when compared to those of an owl (A, B) and the obvious differences they have with those of a noisy flier, in this case a pigeon (C, D). While I am in no way trying to compare the functionality of a feather with that of the pterosaur membrane, the presence of trailing edge structures would almost certainly function in a similar way to other noise reduction structures.
Jeholopterus shares a couple of similarities with that of the barn owl: they both use a slow flight while hunting and both were active during times of darkness or at least periods of low light, but there the similarities end. Jeholopterus was almost certainly an insectivore rather than hunting small vertebrates and so it is not immediately apparent how effective a noise reducing structure like this would have been (hearing range of insects anyone?). So could Jeholopterus have used its trailing edge structures to break down the vortex shed off its wing? If so it would have flapped and glided over the darkening Mesozoic landscape using a combination of slow flight speed, high maneouverability and specialised fibres to reduce the noise frequency of the wings, snapping up insects as it went. Certainly some food for thought regardless."
"Here we’ll compare Batrachognathus [Anurognathidae pterosaur] with its modern analogs among birds, the swift (Apus apus, Figs. 2) and the nightjar (Caprimulgus), both members of the Apodiformes.""With their stiff, elliptical-tipped, narrow-chord wings, nighthawks remind me of anurognathids."
Perhaps binocular vision has been ignored by pterosaur workers largely because no others have bothered to accurately reconstruct the skulls of the only pterosaurs with substantial binocular vision, the owl-like anurognathids.
Most owls have relatively large, rounded wings. The wings are broad, with a large surface area relative to the weight of the bird i.e. a low wing loading. This allows them to fly buoyantly and effortlessly, without too much flapping and loss of energy. They can glide easily and fly slowly for long periods of time. Many species use this slow flight to hunt ground-dwelling prey from the air. 

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