Literature

Although parrots are familiar birds today, they are very sparsely represented in the fossil record. This means thinking is largely unconstrained by data. The discovery of two fossil parrots from the Lower Eocene of Denmark has made a significant change to this situation. The new fossils are considered to predate the previous 'oldest parrot' by 40 million years.

Jardine's Parrot (Source: here)

Of the two fossil birds, one is considered a member of the "stem group" and the other (Mopsitta tanta) a representative of "crown group" species. The implication is that stem and crown species co-existed.

"Mopsitta tanta is in many respects, more similar to Recent Psittaciformes than to any other Palaeogene psittaciform. Although it is not absolutely certain on the basis of preserved features (humeral morphology cannot be entirely diagnostic at this level), it is highly likely that Mopsitta tanta is a member of Psittacidae, therefore providing further support to the hypothesis of an early Eocene (or earlier) radiation of Psittaciformes; it is likely that representatives of crown-group Psittaciformes such as Mopsitta, existed in the Early Eocene alongside their stem-group counterparts Pseudasturidae and Quercypsittacidae."

The main focus of this blog concerns the rapidity of the radiation. Although Darwinists like to emphasise gradualism, with a slow pathway linking stem and crown species, here they are found together almost at the beginning of the Tertiary (which is the earliest many palaeontologists would put them). It's another reminder that speciation is not Darwinian, and the mechanisms that explain faunal radiations are currently unknown.

As a postscript, it is worth revisiting Thomas Stidham's 1998 report of a parrot jawbone from the Cretaceous. This raised many eyebrows because it was so early. The consensus seems to be that it was misidentified. "Dyke and Mayr (1999) considered it to be of uncertain taxonomic affinity because of the fragmentary nature of the material and the possibility that it could be from any number of other taxa, such as a caenagnathid-like theropod dinosaur". Whilst caution is justified, there is a possibility that judgments have been influenced by the low credibility of finding a Cretaceous parrot. With the confirmed presence of modern parrots in the Lower Eocene, credibility should no longer be an issue.

Two new parrots (psittaciformes) from the Lower Eocene Fur Formation of Denmark
DAVID M. WATERHOUSE, BENT E. K. LINDOW, NIKITA V. ZELENKOV, GARETH J. DYKE.
Palaeontology, 51(3), May 2008, 575-582 | doi:10.1111/j.1475-4983.2008.00777.x

Abstract: Two new fossil psittaciform birds from the Lower Eocene 'Mo Clay' (Fur Formation) of Denmark (c. 54 Ma) are described. An unnamed specimen is assigned to the extinct avian family of stem-group parrots, Pseudasturidae (genus and species incertae sedis), while a second (Mopsitta tanta gen. et sp. nov.) is the largest fossil parrot yet known. Both specimens are the first fossil records of these birds from Denmark. Although the phylogenetic position of Mopsitta is unclear (it is classified as family incertae sedis), this form is phylogenetically closer to Recent Pstittacidae than to other known Palaeogene psittaciforms and may, therefore, represent the oldest known crown-group parrot.

A lower jaw from a Cretaceous parrot
Thomas A. Stidham
Nature 396, 29-30 (5 November 1998) | doi:10.1038/23841

All known Cretaceous bird fossils representing modern higher taxa are from the aquatic groups Anseriformes, Gaviiformes, Procellariiformes and Charadriiformes. Here I describe a toothless avian dentary symphysis (fused jawbone) from the latest Cretaceous of Wyoming, United States. This symphysis appears to represent the oldest known parrot and is, to my knowledge, the first known fossil of a 'terrestrial' modern bird group from the Cretaceous. The existence of this fossil supports the hypothesis, based on molecular divergence data, that most or all of the major modern bird groups were present in the Cretaceous.