Palynology studies organic particles called palynomorphs, including pollen, spores, and dinoflagellate cysts. It provides important clues about dating strata and inferring climatic information. Palynology has contributed to the study of Earth’s past, including the earliest real fossils, acritarchs, and the first evidence of terrestrial life. Palynology can also be used in forensic investigations.
Palynology is the science of palynomorphs, organic particles ranging in size from 5 to 500 micrometres. Sometimes, but not always, it includes the study of siliceous or calcareous palynomorphs such as diatoms or foraminifera. The word comes from the Greek and means “scattered or sprinkled forms”. Typical palynomorphs are pollen grains, dinoflagellate cysts, spores, ostrocods, phytoliths, acritarchs, chitinozoans, and scolecodonts. Other materials studied include organic particulate matter (POM) and kerogen, always present in sedimentary rocks. Palynomorphs can be contemporary or fossilized and millions or even billions of years old.
Palynology covers the study of many important microfossils. Because of their abundance, some palynomorphs provide important clues about the dating of strata (biostratigraphy) or the inference of climatic information about a long past geological period. Palynology is considered a branch of earth sciences and biology, with a focus on micropaleontology and paleobotany. Three useful tools for the palynologist are 1) acids, for burning inorganic material and revealing palynomorphs, 2) a sieve, for capturing particles of the desired size, and 3) a microscope, preferably a powerful scanning electron microscope, for obtaining a detailed image of the palynomorph under consideration.
Palynology has made various contributions to the study of the Earth’s past. For example, acritarchs, small fossils thought to be mostly algae cysts, are the earliest real fossils in the fossil record, dating back two billion years, over a billion years before the first multicellular life appeared. About a billion years ago, acritarchs became larger and more complex, demonstrating evolution into single-celled organisms, and acquired spikes, signaling the first appearance of defense against predation. During the worst ice age in Earth’s history, the Cryogenian, about 700 million years ago, numerous acritarchs are found, demonstrating that single-celled organisms fared well during this freezing period.
Two important palynomorphs besides the acritarchs are the scolecodonts, the jaws of marine annelid ketognathic worms, and the chitinozoans, flask-shaped marine palynomorphs of unknown affinity. Scolecodonts give us information about ancient annelids, which otherwise rarely fossilize due to their soft bodies, and are useful biostratigraphic indicators for their rapid evolution and distinctive features.
Some of the earliest fossil evidence of terrestrial life comes from studies in palynology. A feature found only in land plant pollen, called a tetrad, has been located in fossilized pollen dating to the Middle Ordovician, 470 million years ago. This probably came from a plant such as liverwort or hornwort, among the first to colonize the area. The first true plant macrofossils do not appear in the fossil record until the early Silurian, about 440 million years ago.
Palynology can also be used to catch scammers. If a murderer hides in a bush before or after committing a crime, he may be covered in that bush’s characteristic pollen. A palynological test on the suspect’s clothes can then exonerate or convict him. This is called forensic palynology.
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