Popular Mineralogy Interesting mineralogy and earth science for the amateur mineralogist and serious collector - #16 _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________ _________________________________________________________________________________________________________________________________________________________________________________________________ The Flying Dragons of The Carboniferous by Andrew A. Sicree ______________________________ Just how big can a bug get? tooth, a reference to the toothy jaws found in most adult dragonflies). Although Meganeuropsis The biggest insect ever to roam the earth didn’t looked much like a huge version of the modern- do much roaming – it flew! We joke about day dragonfly, there are some important mosquitoes big enough to carry off pets and small differences between the two groups. Dragonflies children, but way back in the Carboniferous coal of both Odonata and Protodonata strong spiny swamps the dragonflies were much bigger than legs and toothy jaws, which facilitate the capture the biggest baddest bug beating its wings down in of prey, but the Protodonata were, of course, the bayous today. enormous compared to modern-day dragonflies. Meganeura monyi is the name that The jaws of the protodonates were larger than paleoentolomogists (scientists who study fossil those of modern dragonflies and their legs were insects) have given to the biggest insect ever to stronger and longer. Their forewings are usually have roamed – or rather flown – the Earth. slightly longer and a bit thinner than their Meganeura monyi was a giant version of a hindwings. These early dragonflies lacked a wing modern dragonfly and had a wingspan greater notch (the nodus) and the pterostigma (the blood- than 30 inches (75 cm) across. By comparison, rich colored patch on a dragonfly’s wing). the largest modern-day dragonfly is Anax Because of the differences between the two strenuous (the Giant Hawaiian Darner or the groups, some authors have suggested that the term “giant dragonfly” be replaced with “griffinfly.” Giant Hawaiian Dragonfly) which has a wingspan up to 7.5 inches (19 cm). Meganeuropsis Insects of the order Odonata first make their permiana is another early dragonfly, found in the appearance in the Triassic (245-208 years ago); early Permian. At 28 inches (71 cm) its wingspan the Protodonata went extinct in the Triassic about rivals that of Meganeura monyi. These bigger- the same time as the earliest dinosaurs appear. than-most-birds dragonflies were predatory, Why so big? capturing other insects in flight and perhaps feeding on small amphibians. Scientists continue to debate the causes of gigantism among ancient insects. One theory The oldest dragonflies states that insect body size is limited by the way Paleoentolomogists report that the oldest an insect gets oxygen. It is thought that insects known dragonfly fossils have been recovered get oxygen by diffusion through their tracheal from Upper Carboniferous (i.e., Pennsylvanian) tubes rather than by “breathing” air in and out. sedimentary rocks in Europe. The Carboniferous Thus, the theory postulates, insects were able to Period stretched from about 360 million years ago grow much larger in the Carboniferous because to about 286 million years ago. It is divided the atmosphere had higher levels of oxygen than (especially in North America) into the the present-day 20%. Other entomologists Mississippian (the Early or Lower Carboniferous contend that insects really do breathe (by means – approximately 360-320 million years ago) and of rapid expansion and contraction of their Pennsylvanian (Late or Upper Carboniferous – tracheal tubes) and thus the atmosphere of the about 320-286 million years ago) periods. Carboniferous need not have been oxygen-rich to support gigantic insects. Meganeuropsis permiana and other now- extinct ancestral dragonflies are classified into the Dragonfly fossils in Appalachia? extinct order Protodonata. Modern-day dragonflies belong to the order Odonata (the Because dragonflies lived near water, one name is taken from “odonto-,” the Greek word for might suspect that they would be likely candidates ©2008, Andrew A. Sicree, Ph.D., [email protected] ~ 9-08-1 ~ Please do not reproduce or extract without permission for fossilization. Paleontology books depict In the Eastern U.S., however, only a few reconstructed dioramas featuring giant dragonflies fossils of Protodonata are known. In 1889, a buzzing through the ancient coal swamps. It is specimen of Paralogus aeschnoides was found in not unusual to find ferns and other plant fossils by Upper Carboniferous rocks near Silver Spring, the ten of thousands preserved in the coal and East Providence, Rhode Island. shale of Appalachian coal mines. Why don’t we A wing fragment in black shale, attributed to find more dragonfly fossils among all these ferns? the species Palaeotherates pennsylvanicus, was One problem may be that, being predators at collected in 1887 from Coxton, one mile north of the top of the insect food chain, large dragonflies Pittston, Pennsylvania. It appears that the weren’t all that common. Another consideration specimen was taken from the Upper Pottsville is that, because of their large but somewhat Formation. A specimen of Tupus durhami was delicate bodies, it would be unusual for an entire collected in 1939 from the roof shale over the No. dragonfly to be preserved intact. Indeed, most 4 Coal at a coal mine in Catoosa (Durham specimens of Carboniferous and Permian fossil Quadrangle), Georgia. Interestingly, it appears dragonflies are known from wing fragments few that this fossil came from the Pottsville Series of of which are even complete wings. Body fossils Georgia and is of Lower Pottsville age – this are even rarer. corresponds approximately to the lower portions of the Pottsville Formation in Pennsylvania. Another factor may be a matter of who is looking for them. Modern coal mining is heavily A more recent in Pennsylvania is that of mechanized and the miner has little opportunity to Palaeothertes analis, which is preserved at the climb down out of his haul truck and search for William Penn Museum in Harrisburg. This fossils. The best hope for finding dragonfly specimen came from the underclay of the Buck fossils is to go to sites at which the rocks are of Mountain #5 anthracite, part of the Allegheny the correct ages and at which fossils of plants are Series. It was found in a strip mine located 400 preserved. Even more important would be to meters eat of benchmark 1271 on the St. Clair- identify sites from which other, smaller fossil Mahoney City Road, in Blythe Township, insects have been recovered. Schuylkill County, Pennsylvania. ©2008, Andrew A. Sicree, Ph.D. _______________________________________________________________________________________________________________ To find a fossil dragonfly Dragonfly fossils were first recognized in Ideal vs. Real Formulas in Minerals Europe. In 1880, fossils of Meganeura monyi were discovered in the Stephanian Coal Measures Mineralogy texts often accompany their near Commentry, France. descriptions of each mineral with a chemical formula. Articles in magazines such as The In North America, protodonatan fossils have Mineralogical Record may also give formulae for been found in rocks from the Grand Canyon in minerals. And mineral lists such as Fleischer’s Arizona. Many important fossil dragonflies have Glossary of Mineral Species (the 10th Edition, been found in the Permian strata of Kansas and released in 2008, authored by Malcolm Black and Oklahoma. The largest complete insect wing ever Joseph A. Mandarino) give mineral formulae, too. recovered is of Meganeura americana, found in The observant collector will notice that sometimes Oklahoma in 1940; it can be seen at the Harvard there are differences between the ways different Museum of Natural History. literature sources report formulae for the same Odonata fossils are more common. The have mineral. been found in the Upper Triassic in Italy, and the This may be because the older source is famous Solnhofen lithographic limestones of reporting the mineral formula as it was known Upper Jurassic age in Germany. China produces originally, while another source is reporting a dragonfly fossils, and some are also found in the more-accurate formula based on later data. Lower Cretaceous Crato Formation of northeast Sometimes, there are perfectly valid, but different, Brazil. This is not a comprehensive list; many ways to write a mineral’s formula. For instance, other localities are known. John Sinkankas’ Mineralogy gives HFeO2 as the ©2008, Andrew A. Sicree, Ph.D., [email protected] ~ 9-08-2 ~ Please do not reproduce or extract without permission formula for the common mineral goethite. Other Encounters of the Third Kind.” Naturally curious, sources use FeO(OH). Note that both give the I stopped too, expecting maybe to see a UFO. No same ratios of Fe, H, and O. UFO’s were visible, but what I did see was a But discrepancies can also be because one wavy pulsing curtain of deep blue and purple – the Northern Lights. literature source is reporting the “ideal” chemical formula while