A millipede fossilized in Cretaceous amber/Thomas Wesener (CC-BY 4.0)
From ScienceDaily:
Over 450 millipedes, fossilized in 100-million-year-old Burmese amber, were recently discovered by a research team. Using micro-CT technology, the scientists identified 13 out of the 16 main groups of modern millipedes amongst them. For half of these groups, the findings also represent the oldest known fossils.
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According to the scientists, most of the Cretaceous millipedes found in the amber do not differ significantly from the species found in Southeast Asia nowadays, which is an indication of the old age of the extant millipede lineages.
On the other hand, the diversity of the different orders seems to have changed drastically. For example, during the Age of the Dinosaurs, the group Colobognatha — millipedes characterised by their unusual elongated heads which have evolved to suck in liquid food — used to be very common. In contrast, with over 12,000 millipede species living today, there are only 500 colobognaths.
Another curious finding was the discovery of freshly hatched, eight-legged juveniles, which indicated that the animals lived and reproduced in the resin-producing trees.
“Even before the arachnids and insects, and far ahead of the first vertebrates, the leaf litter-eating millipedes were the first animals to leave their mark on land more than 400-million-years ago,” explain the scientists. “These early millipedes differed quite strongly from the ones living today — they would often be much larger and many had very large eyes.”
The larger species in the genus Arthropleura, for example, would grow up to 2 m (6.5 ft) long and 50-80 cm (2-3 ft) wide — the largest arthropods to have ever crawled on Earth. Why these giants became extinct and those other orders survived remains unknown, partly because only a handful of usually badly preserved fossils from the whole Mesozoic era (252-66-million years ago) has been retrieved. Similarly, although it had long been suspected that the 16 modern millipede orders must be very old, a fossil record to support this assumption was missing. Paper. (open access) – Thomas Wesener, Leif Moritz. Checklist of the Myriapoda in Cretaceous Burmese amber and a correction of the Myriapoda identified by Zhang (2017). Check List, 2018; 14 (6): 1131 DOI: 10.15560/14.6.1131 More.
We can guess one reason the two-metre millipede might not have survived: There were getting to be lots of large animals around and a two-metre millipede might have a hard time finding rocks to hide under.
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See also: Researchers: Flowers bloomed in early Jurassic, 50 million years earlier than thought “Researchers were not certain where and how flowers came into existence because it seems that many flowers just popped up in the Cretaceous from nowhere,” explains lead author Qiang Fu” It now looks as though they just popped into the Jurassic from nowhere.
Feathers originated 70 million years earlier than thought It certainly is “amazing,” as Professor Benton says, that a complex array of features appeared 250 million years ago, rather abruptly, just as life was recovering from the Permian extinction. Would anyone have predicted that? Talk about “fossil rabbits in the Cambrian.”