Detection of lost calamus challenges identity of isolated Archaeopteryx feather

Daniela Schwarz,Michael Pittman,Xing Xu,Thomas G. Kaye,Gerald Mayr

doi:10.1038/s41598-018-37343-7

Abstract

In 1862, a fossil feather from the Solnhofen quarries was described as the holotype of the iconic Archaeopteryx lithographica. The isolated feather’s identification has been problematic, and the fossil was considered either a primary, secondary or, most recently, a primary covert. The specimen is surrounded by the ‘mystery of the missing quill’. The calamus described in the original paper is unseen today, even under x-ray fluorescence and UV imaging, challenging its original existence. We answer this question using Laser-Stimulated Fluorescence (LSF) through the recovery of the geochemical halo from the original calamus matching the published description. Our study therefore shows that new techniques applied to well-studied iconic fossils can still provide valuable insights. The morphology of the complete feather excludes it as a primary, secondary or tail feather of Archaeopteryx. However, it could be a covert or a contour feather, especially since the latter are not well known in Archaeopteryx. The possibility remains that it stems from a different feathered dinosaur that lived in the Solnhofen Archipelago. The most recent analysis of the isolated feather considers it to be a primary covert. If this is the case, it lacks a distinct s-shaped centerline found in modern primary coverts that appears to be documented here for the first time.

Highlights

One of the best known and most iconic of fossil vertebrates, specimens of the “urvogel” Archaeopteryx have been found for more than a century in the Solnhofen limestones of Southern Germany[1]
During an examination of the Berlin slab, a geochemical halo of the missing calamus was recovered for the first time using Laser-Stimulated Fluorescence (Fig. 1)
The outline of the isolated feather was superimposed onto a version scaled to match the width of the most similar secondary feather in the Berlin specimen (Fig. 2)

Summary

Introduction

One of the best known and most iconic of fossil vertebrates, specimens of the “urvogel” Archaeopteryx have been found for more than a century in the Solnhofen limestones of Southern Germany[1]. During an examination of the Berlin slab, a geochemical halo of the missing calamus was recovered for the first time using Laser-Stimulated Fluorescence (Fig. 1). The distal rectrices of Archaeopteryx are extremely long and symmetrical in outline at the tip (eleventh specimen: Fig. 2E of18), two features absent in the isolated feather.

Results

Conclusion