Insects that walked with dinosaurs: exceptional preservation in Cretaceous amber

I've been looking again at some amazingly well-preserved insects trapped in Cretaceous amber.

Amber is in some ways the best preserving medium of fossil plants and animals known. The fossils are preserved in three dimensions, with great surface detail, and allow snapshots of interactions between animals or between animals and the flows of resin that engulfed them. No other style of exceptional fossil preservation can compare.

The oldest ambers with included animal fossils date back to the Triassic, but the best known early occurrences are Cretaceous in age, from Lebanon, France, Burma/Myanmar and New Jersey (USA). The New Jersey material comes from the Raritan Formation (Turonian, ca 90 Ma), excavated (from lignite occurring 6 to 10 feet below the surface) at a locality near Sayreville, New Jersey, USA. The amber is thought to have been produced by a forest of Cupressaceae in a warm temperate or sub-tropical environment (Grimaldi et al. 2000).

The amber represents aged, hardened resin that once dripped from Cretaceous trees. Sometimes complete elongate "stalactites" of amber can be found, recording multiple flows of resin and the trapping of passing insects and arachnids. A particularly fine example, with a trapped 3 mm wasp, is shown below.

Under a microscope, after much patient searching through numerous pieces of amber, a variety of small arthropods can be observed, often with spectacularly good preservation, such that "they look as if they were alive this morning" despite their 90 to 100 million years of age.

Very occasionally a larger insect can be found, clearly visible to the naked eye, and one of the most dramatic examples known from the New Jersey amber is this very ancient mantis.

Mantids are fascinating insects. They stand their ground and watch you carefully, assuming a martial stance if they consider you a threat. I've met them in Spain, Gabon, Oman and Costa Rica and always enjoy the encounter.

Strange to think that the glowing example shown above walked the Earth in the time of dinosaurs.


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