Wednesday, April 28, 2010

Context - The current dinosaur-based conception

To put this subject (of the development of pterosaurs into modern birds) in context, it is good to take a quick look at the current evolution opinion about the development of modern birds. Current evolution theorists have conceived a series of creatures based on dinosaurs leading to modern birds. Here is a picture of that series:

This series of creatures lacks credibility. The alternative that birds developed from pterosaurs is exceptionally more credible, as this blog will lay out over the course of a number of posts.

Here is a good summary of the dino-to-bird idea:

And see the chart in the Relationships section on this site:

Also here is some history:
"In 1969, this dinosaur was described and named Deinonychus by John Ostrom of Yale University.[21] The next year, Ostrom redescribed a specimen of Pterodactylus in the Dutch Teyler Museum as another skeleton of Archaeopteryx.[22] The specimen consisted mainly of a single wing and its description made Ostrom aware of the similarities between the wrists of Archaeopteryx and Deinonychus.[23]
In 1972, British paleontologist Alick Walker hypothesized that birds arose not from 'thecodonts' but from crocodile ancestors like Sphenosuchus.[24] Ostrom's work with both theropods and early birds led him to respond with a series of publications in the mid-1970s in which he laid out the many similarities between birds and theropod dinosaurs, resurrecting the ideas first put forth by Huxley over a century before.[25][26][27] Ostrom's recognition of the dinosaurian ancestry of birds, along with other new ideas about dinosaur metabolism,[28] activity levels, and parental care,[29] began what is known as the Dinosaur renaissance, which began in the 1970s and continues to this day.
Ostrom's revelations also coincided with the increasing adoption of phylogenetic systematics (cladistics), which began in the 1960s with the work of Willi Hennig.[30] Cladistics is a method of arranging species based strictly on their evolutionary relationships, using a statistical analysis of their anatomical characteristics. In the 1980s, cladistic methodology was applied to dinosaur phylogeny for the first time by Jacques Gauthier and others, showing unequivocally that birds were a derived group of theropod dinosaurs.[31] Early analyses suggested that dromaeosaurid theropods like Deinonychus were particularly closely related to birds, a result which has been corroborated many times since.[32][33]"

This is also noteworthy:

Avialae vs. Aves

"Gauthier[3] (page 34) identified four conflicting ways of defining the term "Aves", which is a problem because the same biological name is being used four different ways. Gauthier proposed a solution, number 4 below, which is to reserve the term Aves only for the last common ancestor of all living birds and all of its descendants. He assigned other names to the other groups.
  1. Aves can mean those advanced archosaurs with feathers (alternately Avifilopluma)
  2. Aves can mean those that fly (alternately Avialae)
  3. Aves can mean all reptiles closer to birds than to crocodiles [ie. dinosaurs and pterosaurs] (alternately Panaves)
  4. Aves can mean the last common ancestor of all the currently living birds and all of its descendants (a "crown group"). (alternately Neornithes)
Under the fourth definition Archaeopteryx is an avialan, and not a member of Aves. Gauthier's restriction of Aves to modern birds has not been widely adopted in the paleontological literature."


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