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Three specimens of a Devonian armored fish, fossilized together. What is preserved are the armored head and the fins of the fish, still articulated. The fish must have died together, are found in close proximity, and are exceptionally well preserved. Slab (about 20 cm in size) on display at the Field Museum of Natural History, Chicago.
This is a specimen (several cm in size) of a fossil jawless fish, from the Devonian of Wyoming, on display at the Field Museum of Natural History, Chicago. Several groups of fish (like the ostracoderms, to which this fish belongs) appear suddenly in the rock record, without many intermediates.
Entire groups of fish found as fossils in Devonian rock layers disappear from higher strata. Among them are osteostracans, like Cephalaspis, a jawless armored fish. Human fingernail for scale. Specimen on display at the Colorado Museum of Nature and Science.
Trimerophytes were leafless vascular plants, with branches departing from the stem in a spiral pattern. This specimen containing multiple stems (several cm in size) is from the Devonian of Quebec, on display at the Field Museum of Natural History, Chicago.
A cast of a famous specimen (about 50 cm in size) of the lobe-finned fish Tiktaalik roseae, from the Devonian of Canada, on display at the Field Museum of Natural History, Chicago. Tiktaalik is often presented as a "missing link" in tetrapod evolution. However, as it often happens, the picture of "sequential transitions" is much more complicated when looked at in detail, with mosaic distribution of characters between various forms.