He Study Of The Gemological Characteristics Of Upper Cretaceous Amber Of Myanmar And The Classification Of A New Caddisfly (Trichoptera: Polycentropodidae) In It

The amber is a kind of natural organic compounds formed from ancient resin buried deep in the ground with complicated geological process.It is the only kind of gemstone that could preserve ancient life in it.Various species of paleontology have been found in the amber from the Late Cretaceous stratum from north Myanmar.The studies of these fossils have get lots of great achievement,giving important evidences form the evolution of the life.The ambers from different localities are always derived from different kinds of plants and found from different geological ages.So the study on the gemmological characteristics of amber from different localities is of significance in identification of the locality of amber and the study of paleontology.This paper randomly choose some amber samples from Dominica,Mexico,Myanmar,Russia,Ukraine,dealing them with conventional gemological methods including specific gravity,refractive index,polarization and UV fluorescence.The result shows:the specific gravity of Myanmar ambers are less than 1.05,slightly smaller than samples from other localities.The refractive index of Myanmar ambers are 1,540 with low volatility.The Myanmar ambers show kinds of colors,such as blue-white,blue-green,green-white,etc,with different light intensities under irradiation with long-wave UV fluorescence;show weak blue-green,blue-white,green-white under short-wave UV fluorescence.The colorful abnormal phenomena of Myanmar ambers is more evident than samples from other localities.The analysis of Fourier Transform Infrared spectroscopy on all samples shows:among 2500²000 cm^-1,the absorption peak caused by C?C stretching vibration of Myanmar ambers is the lowest,followed by Dominican sample,all smaller than the absorption peak of Baltic and Mexio samples;the absorption peak at 1740 cm^-1?caused by C=O stretching vibration in COOH?and 1645 cm^-1?caused by C=C double bond stretching vibration?of Myanmar ambers is weaker than samples from other localities;the absorption peak at 1450 cm^-1?caused by C-CH₂ symmetrical bend vibration?and 1380 cm^-1?caused by C-CH₃ symmetrical bend vibration?of Myanmar ambers is higher than the samples from other localities except Mexico sampes;among 1022⁹70 cm^-1,the absorption spectra of Myanmar ambers make“M-shaped”,different from“Baltic shoulder”in Russian and Ukrainian samples;the absorption peak at 890 cm^-1?caused by=C-H out-of-plane bending vibration?is abent in Myanmar ambers,different from the samples from other localities.Myanmar ambers could be well distinguished from the ambers from other localiti es,through the conventional gemological methods and spectral tests above.It also pro vides the scientific evidence for the localities of the fossils preserved in amber.This paper also makes study on the Trichoptera fossil preserved in the Myanmar amber.A new species of Polycentropodidae,Tridenappendix macularis gen.et sp.nov.,is described,and the phylogenetic result indicates the new species is the basal-most Polycentropodidae.The new species reported shows a taxonomic diversity of Polycentropodidae in Myanmar about 100 Ma,suggesting an older age for the origin of this group,supporting the molecular data-based hypothesis that Polycentropodidae originated at 119 Ma.The function of wing spots of the new specied is sldo discussed.