EVIDENCE OF TEIASSIC IXSECTS — WALKER 141 



Wlietlier the heart-wood borers of Group 2 attacked only the dead 

 trees cannot be determined, since no specimens have been found show- 

 ing tlie workings of both groups on the same log section. 



Recent discoveries of beautifully preserved leaves of ferns and 

 cycads lead one to believe that there is a possibility of someday 

 finding fossil insect remains in these remarkable, fine-grained, paper 

 shales of the Chinle. 



Numerous questions will undoubtedly arise in the minds of many 

 regarding these very brief generalizations. It may be mentioned, 

 however, that the Coleoptera are recorded as far back as the Triassic, 

 and they were numerous in the Jurassic formation. Since we know 

 that the buprestids date back many geological periods, it seems 

 logical to believe that some form of larva or borer could have infested 

 the trees of the great Triassic forests. 



There are numerous trails on the thin, fine-grained sandstones and 

 flagstones of the Petrified Forest area that appear to have been 

 made by some arthropod, but there is no reason for assuming that 

 these trails were made by the adult beetles whose larvae worked the 

 burrows in the trees. 



REFERENCES 



Bbues, Charles Thomas. 



1936. Evidences of insect activity preserved in fossil wood. Journ. Pal., 

 vol. 10, no. 7, pp. 637-643, 6 figs. 

 Fernald, Henry Torsey. 



1921. Applied entomology, xiv-|-386 pp., 388 figs. 

 Lull, Richard Swann. 



1915. Triassic life of the Connecticut Valley. Connecticut State Geol. and 

 Nat. Hist. Surv. Bull. 24, 285 pp., 126 figs., 3 maps, 12 pis. 

 LuTZ, Frank Eugene. 



1918. Field book of insects, x-f509 pp., 101 pis. (many col.). 

 ZiTTEL, Karl Alfred von. 



1913. Text-book of paleontology, vol. 1, 839 pp., illus. (Edited by Charles 

 Rochester Eastman.) 



U. S. GOVERNMENT PRINTING OFFICE: 1939 



