While reading Dawn of the Dinosaurs, I stumbled across some interesting critters that the author took pains to cover. One of them was the so-called monkey-lizards, the Drepanosaurs. It's not every day that you get to see something that looks like a bizarro world cross between a chameleon, anteater, and a vague attempt at a vertebrate scorpion. I wonder if anyone has examined the drepanosaurs for grooves in their tail claw? The Hairy Museum of Natural History has a bunch about them in the link above.
However, wrt to Ward et al's low oxygen hypotheses, it occurred to me that one of the ways that you can test this is by the size of the terrestrial invertebrates. Arthopods have a less efficient oxygen extraction system than do the vertebrates. If the oxygen content dropped, the size of insects ought to fall. To some extent this has been observed. However, in DotD, the author laments that there isn't much work being done on invertebrates during the Triassic. One notable exception was the work by Gorochov in Kyrgyzstan. He found the titanoptera.
What are they? They're an order of insects that was restricted to the Triassic. They are interesting in many ways. As you all know, I am not much of an enthusiast for invertebrate paleontology. Show me some good ole bones, dagnabbit. However, what's so impressive about the titanopterans was that there was a member called Gigatitan vulgaris...with a 12 inch (30 cm) wingspan! If the reconstruction in the book is at all accurate - and I cannot say since I cannot find a single image online - then it looks like its length was somewhere around 6 to 8 inches (15 to 20 cm). it appears to be built much like a cicada and the arms of a praying mantis. Mass wise, it's pretty nontrivial. It looks to be as large or larger than our current bug-type friends. However, I am not a invertebrate paleontologist. The correct mass/volume work ought to be be done by one of them instead of me eyeballing a rendition.
However, it ought to be noted that the largest bugs today are not much bigger if at all: here and here. Note: moths and butterflies are built lighter than the rendition of G vulgaris. Assuming that G vulgaris is an active flier, then either it had a better O2 intake system or something is amiss.