Tuesday, April 19, 2016

Therapsids and You

Testing… Testing…
As this is my first post on LITC I’d like to say “Hello!” I live in South Africa, in the south- western windy end that’s known as the Cape of Good Hope (You know, the place the survivors travel to at the end of the 2012 movie…)
Anyway, I’ve pretty much always been a fossil nerd. As kids my twin sister and I would set up our own excavations. We’d dig up things we thought were dinosaur fossils with tools we found in our parents garage. Nowadays my love of paleontology is not restricted to dinosaurs. In South Africa we have a diverse range of geological formations that have preserved many different creatures from all across the expanse of time. One such group of creatures is a group that is very close to my heart, a group of animals that is not very well known: Therapsids.  
What are Therapsids?
Therapsids evolved in the middle Permian, around 260 million years ago. Therapsid fossils are not unique to South Africa. There are rich finds of these animals in Russia, though South Africa is where these Therapsids were first discovered. The Therapsids belong to a larger group of animals called the Synapsids (of which mammals are the only living examples) and a particularly well known Synapsid from North America  is Dimetrodon.
But Dimetrodon is a dinosaur right? Nope, wrong. But then why have I been finding Dimetrodon figurines alongside T.rex since childhood? Because Therapsids are so poorly understood. Also, let’s admit they do look pretty wild with that giant, colorful fan stuck to their backs. But Dimetrodon is not a dinosaur. So what was it, a reptile? Let’s return to the definition of a Synapsid.

Original artwork: Charles R Knight

Everybody Let’s Not Walk the Dinosaur
Synapsid is an umbrella term referring to a lineage of animals both living and extinct that evolved from Amniotes, early tetrapods that were terrestrial and bred on land. Reptiles and Synapsids both have this common ancestor; however, they were two different lines of descent and this cannot be stressed enough. Lizards, snakes, crocodiles, dinosaurs and the avian dinosaurs, birds, are all groups of animals we’re familiar with tracing their ancestry back to Reptiles.
But what are Synapsids? While early ones like Dimetrodon superficially resembled reptiles and dinosaurs, they were not reptiles. These animals were the ancient relatives and ancestors of mammals, including Humans.  In South Africa, a group of Synapsids named the Therapsids reigned as the dominant fauna for over 40 Million years, and included a bizarre group of animals that could have come straight out of a science-fiction novel. Gorgonospians and Therocephalians had long sabre-like canines, similar to the sabre-toothed cats that evolved much later and prowled the primeval flood plains of the Great Karoo, at a time when South America, Africa, India, Antarctica, and Australia were joined forming a single giant southern continent called Gondwana. Dog to cow-sized dicynodonts were tusk-bearing herbivores, who fed using a tortoise like beak. They were also the main prey of the gorgonopsians and therocephalians. Smaller meerkat-sized animals called Cynodonts included the ancestors of mammals and may even have had whiskers.
However, life on Earth never came closer to complete annihilation than it did at the end of the Permian period 252 million years ago, when 90% of all life (including the therapsids) was eradicated due to a run-away greenhouse warming event at that time. Fossil remains of these animals are found in the Karoo Basin today, and tell their story to Palaeontologists. A few of the small, burrowing therapsids species managed to survive and their descendants, the mammals, eked out a living through the Mesozoic (perhaps dodging the gargantuan steps of sauropods and T. rex!) The amazing part of this story is that the only group of Synapsids alive today are mammals, and us. Perhaps if our minute burrowing ancestors were not so resourceful we would not be here.
Therapsids and other synapsids are amazing evidence for the wonder of evolution. The fact that we humans can trace our ancestry back to these animals… I can’t get over how amazing that is. It’s something we should all know about.  In South Africa the fossil preservation is of such high resolution that the transition from therapsid to mammal can be tracked through time using these animals. Also we can now safely say that there are no reptile- people after all because humans did not evolve from reptiles…

Source: Flickr


  1. Fantastic first post - it's great to have you on board! Of course, synapsids are still smelly and inferior when compared with the Majestic Ones (i.e. dinosaurs), but you do write wonderfully about them.

    1. Thanks, Marc! Well, I will have to take your claim that Synapids were smelly as pure conjecture lol.

  2. Fantastic to see this subject getting some coverage. It's hard to find much reading material that covers this period of pre-history. Sure: it gets a cursory page in the larger Dinosaur books, but it always seem strange the so little time is devoted to the 150m years between Ichthyostega and the Dinosaurs.

    1. Yes, it really is difficult finding anything factual on these animals in the mainstream. I have to chat with paleontologists who study these guys to get any proper details on them. I'm hoping to try change this :)

  3. "Anyway, I’ve pretty much always been a fossil nerd. As kids my twin sister and I would set up our own excavations. We’d dig up things we thought were dinosaur fossils with tools we found in our parents garage."

    I can't help but think there's gonna be a twist where Gina is really Gina's twin sister & the real Gina is mysteriously missing. :P

  4. Wonderful first post! Thank you, Gina, and welcome!

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  6. If I recall pelycosaur grade animals like Dimetrodon are not therapsids like gorgonopsids and mammals, but more basal synapsids. Or am I mistaken ?

    1. Yes, you're right. Therapsids were a group of animals that are classified within the Synapsid group. Pelycosaurs were probably one of the first group of Synapsids to evolve. I just used Dimetrodon as an example for my first post as this animal is so pervasive in the media, but only because it so often gets lumped in with Dinosaurs. Also, Therapsids evolved later on after the Pelycosaurs became extinct so I wanted to make Therapsids more relateable to anyone who didn't know what they were.

      You likely know this, but the name Synapsid also describes the type of skull Dimetrodon (Pelycosaurs) and Therapsids had. Animals from the Synapsid line, which includes us mammals, have only one temporal fenestra behind the eye, which is our temple. Dinosaurs and other reptiles are Diapsids and so they have two skull openings other than their orbits.

  7. I love this topic.

    I think maybe it was mentioned before, but Mark Hallett did a great and colorful two-page family tree of extinct therapsids for the November 1982 issue of Science Digest magazine. Some of the coolest visual representations of therapsids I've ever seen.

    Here is the left half:

    Can't find the right half online right now. I've seen it before, though.

    Hallett also did a great painting of a small pack of Cynognathus dining on their kill, a dicynodont:

  8. I'm super thrilled to welcome you here, Gina! And I'm really looking forward to your upcoming posts. :D

  9. Heya, fellow S. African here - great first post! I'm guessing you've been to the wonderful Iziko museum?


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