A selection of fossils in the natural history collection at Whangarei Museum includes samples from geological time periods like, Triassic, Jurassic, Cretaceous and Miocene epochs. Among these ancient specimens are plant, marine and animal fossils dating back millions of years.
Fossils can be divided into several different categories - body fossils, moulds and casts, petrification fossils, footprints and trackways, and coprolites (dung). The most common types found are body fossils from the hard parts of the body such as bones, claws and teeth, and fossilised traces, called ichnofossils, which are footprints, nests, coprolites or toothmarks.
Within the museum collection are a number of ancient fossilised teeth, including those from a mammoth, ichthyosaur and megalodon, the later an inclusion in a new marine exhibit later this month.
Megalodon, meaning "big tooth," is an extinct species of shark that lived approximately 23 to 26 million years ago. They were the biggest shark that ever lived, growing to a suggested maximum length of nearly 18m, dwarfing the infamous dinosaur Tyrannosaurus Rex.
No megalodon skeletons have ever been found. Being made of cartilage which rarely fossilises, no one is really certain what these creatures looked like, although palaeontologists are able to make an educated guess. All that remains of this prehistoric ocean monster are teeth and a few vertebrae.
Before they were recognised as shark's teeth, Megalodon teeth were mistakenly identified as moon rocks or petrified tongues of dragons and giant serpents. In 1666, a naturalist studying the teeth of great white sharks, made the realisation that these "tongue stones" were actually shark's teeth.
A surprising amount of information can be garnered from fossil shark teeth, including where they lived, their diet and their size. Shark's teeth are the most abundant type of shark fossil, in part because sharks shed thousands throughout their lifetime.
Megalodon ruled the seas for about 25 million years before becoming extinct about two million years ago. Their teeth have been discovered all over the world, many finding their way into museum collections, including Whangarei Museum.
Fossil collecting is an historic pastime and fascinating hobby. Anyone can experience the thrill of finding evidence of prehistoric creatures and the environments they lived in - you just need to know where to look! The Whangarei Rock and Gemstone Club situated in the grounds of Kiwi North may be a good place to start.
■ Natalie Brookland is collection registrar, Whangarei Museum at Kiwi North.
