George Cody of the Carnegie Institute for Science lead a team of researched that discovered the components of chitin in arthropod fossils as early as the Paleozoic era. The research was reported at the Carnegie Institute web site and published in the journal Geology on February 7, 2011.
Arthropods are invertebrate animals that have an exoskeleton (an external skeleton). Arthropods include insect, spiders, crustaceans and are the most numerous group of animals in existence.
The exoskeleton of arthropods are made of cuticle, a non cellular material secreted by the epidermis. The cuticle consists of three main layers: the epicuticle, a thin outer waxy coat that moisture-proofs the other layers and gives them some protection; the exocuticle, which consists of chitin and chemically hardened proteins; and the endocuticle, which consists of chitin and unhardened proteins. Chitin is a modified polysaccharide (sugar) that is modified by bonding to a protein matrix to form the exoskeleton in arthropods.
Cody and his team used low energy x-ray absorption spectra to analyze the chemical; composition of the Paleozoic arthropods and found the majority of carbon, nitrogen, and oxygen found in these ancient arthropods came from chitin. The chitin had been degraded over time but the researchers state that the durability over time may be due to the epicuticle.
The researchers concentrated on a 310 million year old scorpion and a 417 million year old eurypterid. The only other proven chitin bearing arthropods dated from 25 million year old Cenozoic fossils and 80 million year old Mesozoic fossils.
The research settles the debate about chitin and exoskeletons in Paleozoic arthropods.
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