May 20. Wingless insects

Modern springtail

Given that we had forests developing by late Devonian time, you might suspect a proliferation of insects as well. You’re probably right. But insects, fragile as they are, are notoriously difficult to preserve, so the record is fairly sparse during most of the Devonian, especially the early and middle epochs of the period. The bugs in the Rhynie Chert, which we talked about on May 8, do include some primitive insects related to modern springtails. Springtails are hexapods, like insects, but technically they fall into a different group of arthropods. The first complete Devonian insect was not described until 2013 – this link is to the paper in Nature about it. That discovery helps fill in a 45-million-year gap in the fossil record of insects.  

All the few insects known from the Devonian are probably wingless – wings didn’t develop, so far as we know, until the Carboniferous, which we’ll cover in June and July. In terms of the rock record, we’ll have to wait until next month before we can really start to talk about insects. Conditions during the Devonian, including a warm climate and all those proliferating plants on land, would lead you to expect a lot of bugs, too, but the fossil evidence is poor. Either there is a preservation problem – there certainly IS a preservation problem, but we don’t know how big a problem it is – or insects were taking longer to evolve and expand into terrestrial ecologic niches than plants did. Or both.

* * *

Sometime about May 20, in the year 526 a.d., an earthquake hit Antioch, in northwestern Syria. The estimated death toll was 250,000 – maybe as many as 300,000, making it among the deadliest earthquakes in recorded history. The location is near the intersection of the tectonic boundaries between the African and Arabian Plates and the smaller Anatolian Plate that occupies most of modern Turkey. Most of the damage was actually caused by fires that followed the quake and burned for many days. The Great Church of Constantine was a victim of those fires.

—Richard I. Gibson

Modern springtail, similar to wingless insects of the Devonian. Photo by Sarefo under GNU free documentation license.