Biology of Australia
Madtsoiids can be traced back further than any other snake group, up to 90 - 100,000 Ma, they are believed to have originated in the Cretaceous, being present on the Gondwanan continents until the Tertiary. Their Australian remains indicate they survived in Australia until the Pleistocene, long after they had died out elsewhere. They were a primitive snake family, known mainly from Gondwana. some have also been found in France and Spain. They are believed to have been constrictors, but their upper jaws appear to have been less flexible than modern constrictors.
The fossil madtsoiid snakes from Australia are the most complete known. At least 1 madtsoiid snake from Riversleigh grew to about 6 m, putting it in the same size range as the anaconda of South America. The madtsoiids from Riversleigh are thought to be related to the Wonabi naracoortensis, a well-preserved specimen, that was also about 6 m long, that was found in the deposits of the Victoria Fossil Cave and Hensck's Quarry near Naracoorte in South Australia.
Some grew as large as pythons, but most were small. They possess many archaic features, especially in the vertebrae, that have been lost in modern snakes. Another primitive feature was their jaws, being less flexible than modern snakes they would not have been able to swallow prey as large as modern snakes of the same size could.
Alamitophis species can be distinguished by a number of features such as a relatively high neural arch and spine, a narrow zygosphene, and the shape of the haemal keel. Snakes and lizards have a process in front of the neural arch - the zygosphene. A. tingamarra, from the Murgon deposit in Queensland, can be distinguished from A. elongatus, from Patagonia by features of the vertebral column.
During the Early Eocene the Murgon fossil site was apparently a swamp or lake. It is not thought they were fully aquatic snakes, probably more like modern snakes that often hunt frogs or other small animals in and around the shallows. Fossil madtsoiids are often found in freshwater deposits, further suggesting that it was indeed the type of habitat they lived in.
Modern snakes living in cool regions in high latitudes are live-bearers, so it seems possible the madtsoiids were also live-bearers.
The madtsoiids went extinct by the end of the Eocene, except for Australia where they survived until about 100,000 years ago.
Michael Archer, Suzanne J. Hand & Henk Godthelp, 2000, Australia's Lost World: Riversleigh, world heritage Site, Reed New Holland
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