A fossil puts an insect evolution benchmark in doubt
· BehindLines newsroom
A tiny fossil head may force a rethink of a much larger timeline. In a statement dated 29 October, London's Natural History Museum presents a fresh examination of Rhyniognatha hirsti, long used to date the beginnings of winged insects. Published on 18 September in Scientific Reports, the study challenges the position assigned to these remains.
An identification based on the jaw
The specimen comes from the Scottish Rhynie deposit, approximately 408 million years old. Discovered in 1926, it preserves only part of a head, measuring less than a millimetre. According to the museum, an interpretation of its jaws proposed in 2004 led to its identification as a very early winged insect.
The team led by Emma Long examined it again using confocal laser scanning microscopy. This method digitally separates structures that remain difficult to distinguish in the fossil.
The scientific abstract reports that the researchers could not find a joint expected to support the earlier classification. However, their comparisons also cannot confidently assign the fossil to a particular lineage among mandibulate arthropods.
Removing a benchmark does not establish a new beginning
The authors therefore recommend that Rhyniognatha should no longer serve as a calibration point for insect evolution. Such a benchmark constrains the dates proposed in evolutionary trees: the identification matters as much as the age of the rock.
The abstract describes a shift of approximately 80 million years in the minimum age of winged insects. This concerns what the fossil record can establish. It does not provide an exact, definitive date for the emergence of flight.
The museum also highlights the value of revisiting old collections with new instruments. Here, the finding chiefly concerns the reliability of an identification that has been repeatedly reused. The animal's identity remains unresolved, even as its use as a chronological marker is challenged.