Today in real time is October 15, 2014. It is also the first day of Zero Hummingbirds at Kates Cabin Bird Sanctuary in Texas. Not one hummer seen today. We had a significant cold front come in with strong North Wind. The last 20 or so birds caught the North Wind and headed South. Yesterday, I got one photo (below) of the one bird I saw all day.......and then, they were gone!
Next, the photos for today are the highlights from August 29th. The migration pics will continue here on the Blog from all of September and 2 weeks in October. Enjoy!
August 29 photostudy:
Link to Album photostudy:
From Wikipedia, the free encyclopedia
Early evolution of birds
See also: List of fossil birds
|Cladogram following the results of a phylogenetic study by Godefroit et al., 2013.|
The earliest known bird (avialan) fossils currently known hail from the Tiaojishan Formation of China, which has been dated to the lateJurassic period (Oxfordian stage), about 160 million years ago. The avialan species from this time period include Anchiornis huxleyi,Xiaotingia zhengi, and Aurornis xui. The well-known early avialan, Archaeopteryx, dates from slightly later Jurassic rocks (about 155 million years old) from Germany. Many of these early avialans shared unusual anatomical features that may be ancestral to modern birds, but were later lost during bird evolution. These features include enlarged claws on the second toe which may have been held clear of the ground in life, and long feathers or "hind wings" covering the hind limbs and feet, which may have been used in aerial maneuvering.
Avialans diversified into a wide variety of forms during the Cretaceous Period. Many groups retained primitive characteristics, such as clawed wings and teeth, though the latter were lost independently in a number of bird groups, including modern birds (Neornithes). While the earliest forms, such as Archaeopteryx and Jeholornis, retained the long bony tails of their ancestors, the tails of more advanced birds were shortened with the advent of the pygostyle bone in the clade Pygostylia. In the late Cretaceous, around 95 million years ago, the ancestor of all modern birds also evolved better olfactory senses.
|Mesozoic bird phylogeny simplified after O'Connor et al., 2013.|
The first large, diverse lineage of short-tailed birds to evolve were the enantiornithes, or "opposite birds", so named because the construction of their shoulder bones was in reverse to that of modern birds. Enantiornithes occupied a wide array of ecological niches, from sand-probing shorebirds and fish-eaters to tree-dwelling forms and seed-eaters. While they were the dominant group of land birds during the Cretaceous period, enantiornithes became extinct along with many other dinosaur groups at the end of the Mesozoic era.
Many species of the second major bird lineage to diversify, the Euornithes ("true birds", including the ancestors of modern birds), were semi-aquatic and specialized in eating fish and other small aquatic organisms. Unlike the enantiornithes, which dominated land-based and arboreal habitats, most early euornithes lacked perching adaptations and seem to have included shorebirds, waders, and swimming and diving species. The later included the superficiallygull-like genus Ichthyornis (fish birds), the Hesperornithiformes, which became so well adapted to hunting fish in marine environments that they lost the ability to fly and became primarily aquatic. The early euornithes also saw the development of many traits associated with modern birds, like strongly keeled breastbones, toothless, beaked portions of their jaws (though most non-avian euornithes retained teeth in other parts of the jaws). Euornithes also included the first birds to develop true pygostyle and a fully mobile fan of tail feathers, which may have replaced the "hind wing" as the primary mode of aerial maneuverability and braking in flight.
Diversification of modern birds
|Basal divergences of modern birds|
based on Sibley-Ahlquist taxonomy
All modern birds lie within the crown group Neornithes (alternately Aves), which has two subdivisions: the Palaeognathae, which includes the flightless ratites (such as the ostriches) and the weak-flying tinamous, and the extremely diverse Neognathae, containing all other birds.These two subdivisions are often given the rank of superorder, although Livezey and Zusi assigned them "cohort" rank. Depending on thetaxonomic viewpoint, the number of known living bird species varies anywhere from 9,800 to 10,050.
Due largely to the discovery of Vegavis, a late Cretaceous neognath member of the duck lineage, Neornithes is now known to have split into several modern lineages by the end of the Mesozoic era. The earliest divergence from the remaining Neognathes was that of theGalloanserae, the superorder containing the Anseriformes (ducks, geese, swans and screamers) and the Galliformes (the pheasants, grouse, and their allies, together with the mound builders and the guans and their allies). The dates for the splits are much debated by scientists. The Neornithes are agreed to have evolved in the Cretaceous, and the split between the Galloanseri from other Neognathes occurred before the Cretaceous–Paleogene extinction event, but there are different opinions about whether theradiation of the remaining Neognathes occurred before or after the extinction of the other dinosaurs. This disagreement is in part caused by a divergence in the evidence; molecular dating suggests a Cretaceous radiation, while fossil evidence supports a Cenozoic radiation. Attempts to reconcile the molecular and fossil evidence have proved controversial.
...this is brendasue signing off from Rainbow Creek. See you next time!