Examining Bird-Like Features in Dinosaurs and Mesozoic Birds Questions Evolutionary Theories

The putative descent of birds from dinosaurs has become established as one of the most popular evolutionary transitions. In recent years, apparent bird-like features have been increasingly detected in theropod dinosaurs, leading to the conclusion that birds are simply "living dinosaurs". The occurrence of a number of bird-typical traits in dinosaurs and Mesozoic birds is here analysed in more detail. In which theropod groups do the traits in question occur, and what is the phylogenetic and stratigraphic position of the genera in question? Is it supported by data that the apparent avian features were added step by step? The cladistic methodology is used to test whether consistent evolutionary hypotheses can be made within an evolutionary interpretive framework in light of the fossil evidence. The following traits or trait complexes are examined: feather types and flight ability, teeth and beak, brain and encephalization quotient, furcula, gastralia, rib cage, sternum, pneumaticity, air sac system and respiration, pelvis and posteriorly oriented pubis, pygostyle, fibula, wrist, and eggs, clutch, and brood care. It was concluded that even after examining the claimed fossil evidence, there are no unequivocal evolutionary transitions. Instead, the evidence confirms the creation of a variety of original basic types (created kinds) that subsequently diversified.

Abstract

Birds are now considered "living dinosaurs" by evolutionary theorists. The putative descent of birds from dinosaurs has become established as one of the most popular evolutionary transitions. In recent years, apparent bird-like features have been increasingly detected in theropod dinosaurs, and a majority of apparent avian traits have been found to be represented in various dinosaur groups. Therefore, a gradual transition from dinosaurs to birds is considered by evolutionary theorists well supported by fossil evidence. Only a few characteristics are considered suitable to distinguish between birds and dinosaurs. Thus, one could no longer draw a line between dinosaurs and birds today according to evolutionists. The occurrence of a number of bird-typical traits in dinosaurs and Mesozoic birds is here analysed in more detail. In which theropod groups do the traits in question occur, and what is the phylogenetic and stratigraphic position of the genera in question? Is it supported by data that the apparent avian features were added step by step? The cladistic methodology is used to test whether consistent evolutionary hypotheses can be made within an evolutionary interpretive framework in light of the fossil evidence. The following traits or trait complexes are examined: feather types and flight ability, teeth and beak, brain and encephalization quotient, furcula, gastralia, rib cage, sternum, pneumaticity, air sac system and respiration, pelvis and posteriorly oriented pubis, pygostyle, fibula, wrist, and eggs, clutch, and brood care. It was concluded that even after examining the claimed fossil evidence, there are no unequivocal evolutionary transitions. Instead, the evidence confirms the creation of a variety of original basic types (created kinds) that subsequently diversified.

Keywords: Dinosaurs, birds, fossils, opposite birds, ornithurans, convergence, creation, evolution

Summary of Findings Assuming an evolutionary emergence the resulting analysis shows that a number of apparent bird-typical traits that occur in theropod dinosaurs would have evolved multiple times convergently and were presumably not expressed at all in phylogenies at the base of the respective groups. For almost all studied traits, convergences have to be assumed more or less frequently due to the mosaic-like distributions. In some cases, different relationships are suggested depending on the underlying trait. This manifests itself, for example, in the fact that a number of genera, measured against established phylogenies, show contradictory trait combinations that make phylogenetic classification more or less difficult. This often mosaic distribution also favors the controversial interpretation that some genera interpreted as avian precursors may be secondarily flightless birds. In this case, their features would be eliminated as evidence for a gradual transition from dinosaurs to birds. Some features continue to show significant jumps.

Based on these findings, the claim of a gradual evolutionary "buildup" of the avian assemblage based on the fossil record is strongly questioned and is not supported by the fossil record for some traits. Moreover, these and other commonly encountered findings do not conform to evolutionary theory expectations and may be considered anomalies:

Based on the distributions of features in early birds and the dinosaurs close to them and their stratigraphic positions, a picture emerges of different mosaics and consequently of a network of similarity relationships. It is not clear which group is at the base of the birds. The large extent of homoplasy means that the cladograms are not stable and new finds can lead to major changes. The oldest bird groups are already strongly differentiated at the base and there are partly also "modern" characteristics in the oldest representatives of a group.

Especially in plumage characteristics, the greatest degree of diversity is seen near the base of the bird groups. Most theropod dinosaur genera that have apparent bird-like features are geologically younger than the geologically oldest birds.

Some findings appear able to be interpreted well from an evolutionary point of view (which does not mean that this interpretation is correct). Some (but by far not all) mosaic forms could possibly be