Avian evolution: the fossil record of birds and its Paleobiological significance

We describe a specimen of the basal ornithuromorphArchaeorhynchus spathulafrom the Lower Cretaceous Jiufotang Formation with extensive soft tissue preservation. Although it is the fifth specimen to be described, unlike the others it preserves significant traces of the plumage, revealing a pintail morphology previously unrecognized among Mesozoic birds, but common in extant neornithines. In addition, this specimen preserves the probable remnants of the paired lungs, an identification supported by topographical and macro- and microscopic anatomical observations. The preserved morphology reveals a lung very similar to that of living birds. It indicates that pulmonary specializations such as exceedingly subdivided parenchyma that allow birds to achieve the oxygen acquisition capacity necessary to support powered flight were present in ornithuromorph birds 120 Mya. Among extant air breathing vertebrates, birds have structurally the most complex and functionally the most efficient respiratory system, which facilitates their highly energetically demanding form of locomotion, even in extremely oxygen-poor environments.Archaeorhynchusis commonly resolved as the most basal known ornithuromorph bird, capturing a stage of avian evolution in which skeletal indicators of respiration remain primitive yet the lung microstructure appears modern. This adds to growing evidence that many physiological modifications of soft tissue systems (e.g., digestive system and respiratory system) that characterize living birds and are key to their current success may have preceded the evolution of obvious skeletal adaptations traditionally tracked through the fossil record.

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Elaborate plumage patterning in a Cretaceous bird

PeerJ ◽

10.7717/peerj.5831 ◽

2018 ◽

Vol 6 ◽

pp. e5831 ◽

Cited By ~ 5

Author(s):

Quanguo Li ◽

Julia A. Clarke ◽

Ke-Qin Gao ◽

Jennifer A. Peteya ◽

Matthew D. Shawkey

Keyword(s):

Fossil Record ◽

Early Stage ◽

Life Changes ◽

Sexual Signaling ◽

Avian Evolution ◽

Chemical Evidence

Integumentary patterns and colors can differentiate species, sexes, and life changes and can inform on habitat and ecology. However, they are rarely preserved in the fossil record. Here, we report on an extremely well-preserved specimen of the Cretaceous bird Confuciusornis with unprecedented complexity, including small spots on the wings, crest, and throat. Morphological and chemical evidence suggest that these patterns are produced by melanin, but unusual preservation prevents assignment of specific colors. Based on comparisons with extant birds, these patterns were likely used for camouflage, although other functions including sexual signaling cannot be ruled out. Our data show that even more elaborate plumage patterns than the spangles in Anchiornis and stripes in Sinosauropteryx were present at a relatively early stage of avian evolution, showing the significance of coloration and patterning to feather evolution.

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Does the fossil record of spiders track that of their principal prey, the insects?

Transactions of the Royal Society of Edinburgh Earth Sciences ◽

10.1017/s026359330300018x ◽

2003 ◽

Vol 94 (03) ◽

pp. 275 ◽

Cited By ~ 1

Keyword(s):

Fossil Record

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Molecular clock tied to fossil record

Nature ◽

10.1038/news041011-2 ◽

2004 ◽

Author(s):

Emma Marris

Keyword(s):

Molecular Clock ◽

Fossil Record

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Darwin's two competing phylogenetic trees: marsupials as ancestors or sister taxa?

Archives of Natural History ◽

10.3366/anh.2012.0091 ◽

2012 ◽

Vol 39 (2) ◽

pp. 217-233 ◽

Cited By ~ 4

Author(s):

J. David Archibald

Keyword(s):

Fossil Record ◽

Evolutionary Biology ◽

Phylogenetic Trees ◽

Charles Darwin ◽

The Other ◽

Charles Lyell ◽

Single Origin ◽

Molecular Studies ◽

Richard Owen ◽

First Time

Studies of the origin and diversification of major groups of plants and animals are contentious topics in current evolutionary biology. This includes the study of the timing and relationships of the two major clades of extant mammals – marsupials and placentals. Molecular studies concerned with marsupial and placental origin and diversification can be at odds with the fossil record. Such studies are, however, not a recent phenomenon. Over 150 years ago Charles Darwin weighed two alternative views on the origin of marsupials and placentals. Less than a year after the publication of On the origin of species, Darwin outlined these in a letter to Charles Lyell dated 23 September 1860. The letter concluded with two competing phylogenetic diagrams. One showed marsupials as ancestral to both living marsupials and placentals, whereas the other showed a non-marsupial, non-placental as being ancestral to both living marsupials and placentals. These two diagrams are published here for the first time. These are the only such competing phylogenetic diagrams that Darwin is known to have produced. In addition to examining the question of mammalian origins in this letter and in other manuscript notes discussed here, Darwin confronted the broader issue as to whether major groups of animals had a single origin (monophyly) or were the result of “continuous creation” as advocated for some groups by Richard Owen. Charles Lyell had held similar views to those of Owen, but it is clear from correspondence with Darwin that he was beginning to accept the idea of monophyly of major groups.

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