SLEEPY KOALAS

The Koala, Phasscolarctos cinereus, is a lovely marsupial native to Australia. These cuddly "teddy bears" are not bears at all.

Koalas belong to a group of mammals known as marsupials. They have pouches on their bellies where their newborns develop. Wee baby Koalas are called joeys. They are born blind and earless but use their strong sense of touch and smell to guide them instinctively up into their mother's pouch when they are born. They live in her pouch for about six months. When they are a little stronger (and braver and get curious) they forage out, riding on their mother's backs until they are about a year old. Adult Koalas love eucalyptus trees and spend their leisurely days eating and napping amongst the foliage.

GONDWANA: EVOLUTION OF A SUPERCONTINENT

The ancient supercontinent of Gondwana, as we think of it, came into being about 500 million years ago. We refer to that time as the Ediacaran, the time of the beginnings of multicellular organisms. These were exotic and primitive beasties, interesting segmented worms, rounded jellyfish-like organisms, enigmatic tubular and sea-pen-like beauties.

Gondwana split into the landmasses we know today about 180 million years ago. Not lost, just reformed as Africa, South America, Australia, Antarctica, the Indian subcontinent and the Arabian Peninsula. Gondwana joined with other landmasses to become Pangea by about 300 million years ago, before morphing again into Laurasia. By the middle of the Eocene, some fifty-five million years ago, only Australia, Antarctica and South America remained as they straddled the South Pole.

Free of ice and the giant marine and flying reptiles, a new line-up of mammals, flightless birds, crocodiles, snakes and turtles thrived in the warm, wet climate, rapidly adapting and dominating the forests, oceans and skies. New and fanciful creatures, the monotremes, marsupials and placentals explored and took root in the Gondwanan forests as conifers gave way to broad-leaved trees in an ever changing landscape.

CHENGJIANG LOBOPODIAN

A rather nice Onychodictyon ferox (lobopod) from the Chengjiang Biota, Lower Cambrian, Yunnan, China. The Lobopodians, or Velvet Worms, are small marine and terrestrial animals averaging about 70 mm in length. All recent forms of these wee beasties are terrestrial. Most of the fossil Lobopodians are marine and closely resemble Aysheaia from the Burgess Shale. Collection of Marc R. Hänsel.

SKØKKENMØDDINGER

Many First Nations sites were inhabited continually for centuries. These sites were both home, providing continuity and community and also formed a spiritual connection to the landscape.

The day to day activities of each of these communities would much like our own. Babies were born, meals were served and life followed a natural cycle.

As coastal societies lived their lives they also left their mark. Sometimes through totems and carvings but almost always through discarded shells and scraps of bone from their food. These refuse heaps contain a wealth of information about how that community lived, what they ate and what environmental conditions looked like over time. This physical history provides a wonderful resource for archaeologists in search of botanical material, artifacts, broken cooking implements and my personal favourite, mollusc shells.

These wonderfully informative heaps of the local gastronomic record provide a wealth of information. Especially those formed from enormous mounds of bivalves and clams. We call these middens. Left over time, these unwanted dinner scraps transform through a process of preservation.

The Danish term køkkenmøddinger (plural) was first used by Japetus Steenstrup, a Danish zoologist and biologist, to describe shell heaps and continues to be used by some researchers. I still prefer middens, but to each his own. Time and pressure leach the calcium carbonate, CaCO3, from the surrounding marine shells and help “embalm” bone and antler artifacts that would otherwise decay. Useful this, as antler makes for a fine sewing tool when worked into a needle. A bone that has had some time to harden through this natural embalming process makes for a fine needle indeed. Much of what we know around the modification of natural objects into tools comes from this preservation.

Calcium carbonate is a chemical compound that shares the typical properties of other carbonates. In prepping fossil specimens embedded in limestone, it is useful to know that limestone, itself a carbonate sedimentary rock, reacts with stronger acids, releasing carbon dioxide: CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l).

Calcium carbonate reacts with water saturated with carbon dioxide to form the soluble calcium bicarbonate. Bone already contains calcium carbonate, as well as calcium phosphate, Ca2, but it is also made of protein, cells and living tissue.

Decaying bone acts as a sort of natural sponge that wicks in the calcium carbonate displaced from the shells. As protein decays inside the bone, it is replaced by the incoming calcium carbonate, making the bone harder and more durable.

The shells, beautiful in their own right, make the surrounding soil more alkaline, helping to preserve the bone and turning the dinner scraps into exquisite scientific specimens for future generations.