
All animals on Earth are related, even though these relationships aren’t always obvious. The reason these relationships are hard to figure out is that despite the diversity of animals we see, they represent a mere fraction of the life that has ever existed on this planet. In fact, one famous palaeontologist estimated that we know of less then 1% of the Earth’s diversity through time.
To understand the relationships between animals better, we have to look back in time, at the extinct ancestors of the animals alive today (animals living today are called ‘extant’).
This diagram (called a cladogram) shows how the five major groups of vertebrate animals are related:-Fish gave rise to the first amphibians, which crawled on to land about 400 million years ago.
-Amphibians and reptiles share a common ancestor about 350 million years ago.
-Mammals and birds evolved from reptiles much later at different times during the Mesozoic Era.
Each of these major transitions was slow. It must be understood that a fish doesn’t become an amphibian overnight. There were many different species of animals that formed that transitory stages between these groups and possessed a unique set of characteristics, a sort of ‘mosaic’ between the two groups.
Now let’s look more closely at the evolution of mammals. Mammals evolved from mammal-like-reptiles, a very diverse groups of animals which are all (unfortunately) extinct. Through time three major groups of mammals evolved:Prototherians - which lay eggs (eg. platypuses and echidnas)
Metatherians - which let young develop in pouches (marsupials such as kangaroos and koalas)
Eutherians – ‘modern mammals’ which give birth to well-developed offspring (this includes many familiar species such as rabbits, elephants, horses, and humans)
The platypus is a prototherian. This ancient group branched off of the mammal tree of life early on before the other two groups. There are many different prototherians in the fossil record but only platypuses and echidnas are still around. So the past there was a great diversity of egg-laying mammals, but sadly, all of those animals except for platypuses and echidnas) are now extinct.
If you are interested in this topic I recommend visiting Date A Clade, which has an excellent (and more comprehensive) cladogram with detailed information on when major groups of animals split away from each other.







Well I have just posted my 100th post. Thanks to my regular readers and welcome to the new ones. I hope I am doing something right, I was recently awarded the Thinking Blogger Award by 


Something has been bothering me the last while. I can’t figure out why Great White Sharks are always depicted as having a big bloody gape? I have researched it a bit but have not come up with any good information. As it I see it though, there are three distinct possibilities:






I have recently discovered blog carnivals (truth be told, my initiation to the blogosphere is recent as well). Blog carnivals and circuses are a great way to get to know your neighbours in the blogosphere and so I have requested to host Oekologie, one of the best travelling blog carnivals around. Oekologie reviews the best ecology and environmental science posts of the month from all across the blogosphere. My turn comes in September so is a way off, but I am looking forward to it! In the mean time check out the happening at the 




Last week I wrote about smugglers who were caught trying to sneak butterflies and chameleons into Croatia. Following that article, a reader sent me an article on some hilarious antics of other criminals who got caught in the act of smuggling strange cargo:
Well I’m sure everybody has seen this sensationalist headline in the last week, instead of tackling the controversy myself, I’ve decided to list a few posts by bloggers who have already posted on the topic:
Thanks to everyone who sent in their entry. The submitted captions include:
This book is not new, but I only discovered recently. If you haven’t read it and enjoy palaeo-humor I suggest you pick it up! It is picturesque, surreal and an equally amusing read for geeks and children:)








Continuing on the whale theme today, an Australian couple has had an extraordinary windfall: walking along a remote beach they found 32-pounds of sperm whale puke, for which the proper scientific word is ambergris. At first this may seem like a disgusting curiosity worth no more than a moment of notice for its scientific value, but in fact the monetary value of the discovery is estimated to be over $1 million USD!
