Chicago ‘Archaeopteryx’ published in Nature

From the abstract
“Here we report on the nearly complete and uncrushed 14th specimen of Archaeopteryx. Exceptional preservation and preparation guided by micro-computed tomographic data make this one of the best exemplars of this iconic taxon, preserving important data regarding skeletal transformation and plumage evolution in relation to the acquisition of flight during early avian evolution.

Earlier the Chicago specimen FMNH PA 830 was considered #13. That changed.

Clearly the Chicago workers are lumpers, not splitters. There is greater value placed on a specimen if a Late Jurassic bird is lumped with the holotype of Archaeopteryx = the London specimen (Fig 2).

The ventrolaterally exposed skull reveals a palatal morphology intermediate between troodontids¹ and crownward Cretaceous birds.

As do all Solnhofen birds.

Modifications of the skull reflect the shift towards a less rigid cranial architecture in archaeopterygids from non-avian theropods.

As do all Solnhofen birds.

The complete vertebral column reveals paired proatlases and a tail longer than previously recognized. Skin traces on the right major digit of the hand suggest that the minor digit was free and mobile distally, contrary to previous interpretations.

First time interaction with the term, ‘the minor digit’ which is usually manual digit 5, or ‘the pinkie’. Birdy theropods have only three manual digits (Fig 1) so the minor digit is likely digit 3.

The morphology of the foot pads indicates that they were adapted for non-raptorial terrestrial locomotion. Specialized inner secondary feathers called tertialsare observed on both wings. Humeral tertials are absent in non-avian dinosaurs closely related to birds, suggesting that these feathers evolved for flight, creating a continuous aerodynamic surface. These new findings clarify the mosaic of traits present in Archaeopteryx, refine ecological predictions and elucidate the unique evolutionary history of the Archaeopterygidae, providing clues regarding the ancestral avian condition.”

We looked at #14 earlier here and here where it nested within the Scansoriopterygidae in the large reptile tree (LRT, 2338 taxa), some phylogenetic distance from the holotype.

Figure 1. The Field Museum Chicago Solnhofenbird is not Archaeopteryx, but related to the n12 private specimen in the LRT. These nest with Scansoriopterygids. ” data-image-caption=”

Figure 1. The Field Museum Chicago Solnhofenbird is not Archaeopteryx, but related to the n12 private specimen in the LRT. These nest with Scansoriopterygids.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg?w=584″ class=”size-full wp-image-89531″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg” alt=”Figure 1. The Field Museum Chicago Solnhofenbird is not Archaeopteryx, but related to the n12 private specimen in the LRT. These nest with Scansoriopterygids.” width=”584″ height=”526″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg?w=584&h=526 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg?w=150&h=135 150w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg?w=300&h=270 300w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2024/11/chicago.archaeopteryx588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. The Field Museum Chicago Solnhofenbird is not Archaeopteryx, but related to the n12 private specimen in the LRT. These nest with Scansoriopterygids.

The figures (1-9) in the Nature article
include many images of the specimen, but no cladogram. The paper is currently behind a paywall.

Figure 2. Most of the complete Solnhofen birds, including Archaeopteryx and the eleventh specimen to scale. ” data-image-caption=”

Figure 2. Most of the complete Solnhofen birds, including Archaeopteryx and the eleventh specimen to scale.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2017/12/archaeopteryx_specimens2.jpg?w=65″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2017/12/archaeopteryx_specimens2.jpg?w=222″ class=”size-full wp-image-29216″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2017/12/archaeopteryx_specimens2.jpg” alt=”Figure 2. Most of the complete Solnhofen birds, including Archaeopteryx and the eleventh specimen to scale.” width=”584″ height=”2698″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2017/12/archaeopteryx_specimens2.jpg?w=584&h=2698 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2017/12/archaeopteryx_specimens2.jpg?w=65&h=300 65w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2017/12/archaeopteryx_specimens2.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 2. Most of the complete Solnhofen birds, including Archaeopteryx and the eleventh specimen to scale. From 2017.

References
O’Connor J, et al (9 co-authors) 2025. Chicago Archaeopteryx informs on the early evolution of the avian bauplan. Nature (2025). https://doi.org/10.1038/s41586-025-08912-4

The Field Museum announces acquisition of ‘Archaeopteryx 13’

After analysis the Chicago 13th ‘Archaeopteryx’ is not another Archaeopteryx