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Let’s escape today’s world and visit an endearing little friend from down under! This sausage-shaped creature was neither a reptile nor a mammal and it lived in what is now Antarctica. The creature’s name is Lystrosaurus, and it has been in the news recently because scientists analyzed its banded tusks and realized that it most likely hibernated during the dark times of winter.
This information is remarkable because Lystrosaurus lived in the Triassic Period–about 250 million years ago. As you might imagine, the world of a quarter of a billion years ago was very different than that of today. Not only had life just experienced the most catastrophic mass die-off in planetary history (the poorly understood end Permian mass-extinction, which ushered in the age of the dinosaurs), but the continents were all annealed together in one huge super continent, Pangea. Even though the contnents were in different places, the land which is now Antarctica was still by the South Pole.
During the time of Pangea, the world was much hotter than now, yet the axis of the Earth was not terribly different–so South Pole winters grew dark. This was a problem for Lystrosaurus, since its dentition indicates it lived on tubers, roots, and vegetation (and other things) which it grubbed up with its cute little tusks. When the world darkened every year, it became hard for lystrosaurus to find food, and so it slumbered.
Despite its dinosaur-like name, Lystrosaurus was a dicynodont therapsid, a sort of proto-mammal which flourished in the late Paleozoic and the early Mesozoic (before dinosaurs monopolized the scene).
To my eyes there is something appealing about the portly dog-sized lystrosaurus, and it amuses me to imagine it dozing through a dark foggy Pangea winter before awakening to run around gobbling up tree fern roots and weird amphibians with tombstone heads. Life has showed up in some strange and remarkable forms over the long years but certain habits and behaviors reappear again and again!
A quarter of a billion years ago a shallow sea covered what is now Hubei, China (the parts of the world that are today Manchuria, South China, and Southeast Asia were large archipelagos in this shallow sea). The warm water was perhaps a meter or so deep–a child could stand in it, and it was filled with proliferating shrimp, worms, and mollusks. The early Triassic was a strange time for life on Earth: the world’s greatest mass-extinction (thus far) had just swept traditional Paleozoic players off the world stage, but the famous stars of the Mesozoic–the dinosaurs–had not yet taken over the land. Peculiar creatures were fast evolving to fill empty ecological niches once filled by now extinct animals.
You are probably wondering what sort of creatures lived in this vanished ocean–and you are in luck, because the answer is amazing! Paleontologists in China discovered the remains of…a marine reptile (?) with a cartilaginous beak. The creature had a rigid body and tail and 4 stubby little flippers for steering and swimming. It also had bony plates on its back like a stegosaurus and tiny little pinpick eyes. Scientists named the creature Eretmorhipis carrolldongi. The most analagous creature in today’s world is the platypus, and, indeed, Eretmorhipis looked like a crazy platypus (combined with a blind penguin and a stegosaurus). The analogy however is rather misleading since, 250 million years ago the first monotremes were probably evolving in the same addled post-apocalyptic world (monotremes are amazing and bizarre, but, sadly, we don’t have a complete fossil record of them, so we have to base some of what we think about them on genetic paleontology which provides a rough timeline).
Eretmorhipis carrolldongi was a hupehsuchian reptile. It was a relative (or maybe a precursor) to the ichthyosaurs which soon took over the world’s oceans and evolved unique graceful mastery of the planet’s oceans before something went terribly wrong. I want to write more about the icythyosaurs (their story illustrates something exceedingly important about life), but before I do that I wanted to share this stubby ridiculous platypus analog creature with you so you can think about the comic reptile rooting around its ancient ocean at night with its beak hunting shrimp and invertebrates with its sensitive beak in the turbid darkness. The world is a mad grab bag and you never know what is going to be successful. We probably out to talk about the end-Permian mass extinction too, but it is the stuff of ultimate nightmares, so I am going to slow walk that post for now… maybe when (if?) we are feeling stronger.
An Iridescent Wasp on a Linen Tablecloth
Today I would like to start a brand new animal category concerning the most gifted of the social insects, the superorder Hymenoptera, which consists of wasps, bees, ants and sawflies (along with some other oddballs which are less frequently mentioned). Hymenoptera are arguably among the most successful creatures on the planet. Their behavior can be almost embarrassingly humanlike and they are famous for building elaborate constructions, going to war, taking slaves, farming fungi, and crafting rigid city-like social hierarchies. However, of all life forms on earth, the hymenoptera are some of the most vividly alien: cuttlefish do seem downright cuddly when compared to the horrifying digger wasps. A sociologist could happily draw parallels between a bee hive and a city until he looked at the details of bee reproduction, at which point he would probably break down and weep.
The Hymenoptera are not as ancient as either the mollusks or the mammals (if it is fair to compare an order with a phylum or a class). They originated in the Triassic and did not develop the successful social organization which is now such a defining feature until the late Cretaceous. The first hymenopterans were the xylidae, a family of sawflies with a minimal presence on earth today but with a long pedigree. These first sawflies fed on the pollen and buds of the conifer stands beneath which the first dinosaurs developed (and under the roots of which the first mammals cowered). The rise of the flowering plants in the Cretaceous led to a leap-forward for these pollen-eaters: complex flowers then evolved in tandem with the hymenopterans. It was also during the Cretaceous that the ants and termites split from the vespoid wasps. The earliest honey bees of the familiar genus Apis evolved at the end of the Eocene bt they were preceded by all sorts of hymenopteran pollinators.
A Sawfly Fossil (Hymenoptera: Symphyta)
I mentioned above that, for all of their familiarity to us, the Hymenoptera are disturbingly alien. In fact as I have been writing this comparatively tame post, a dreadful sense of formication has stolen over me and I find myself brushing phantom ants from my limbs and feeling the terrible pang of yellowjacket stings from childhood. The hymenoptera are frequently the basis of the extraterrestrial enemies in science fiction. Although people are occasionally stung to death by wasps or ripped apart from within by driver ants, it is something larger and less tangible which makes the hymenoptera such reliable villains. I have watched the soldier bees snip the wings off of wasps trying to invade my grandfather’s bee hive and then toss the invaders’ writhing bodies from the painted ledge—all while a river of worker bees went out and came back laden with pollen. There is an alarming touch of civilization to these social insects: a hint that they are utilizing the same kinds of organization and communication which have made humans such a success. And, in fact, the social insects are a huge success—ants alone are estimated to constitute a substantial portion of the animal biomass of earth (to say nothing of termites, bees, wasps and the rest).
Yellow Jackets on a Coke Can (photo by the fearless Alan Cressler)
Of course this success has broad ramifications. The hymenoptera are everywhere in nature and they also play a huge part of human culture. Indeed the very name of this blog is a play on words between my surname and the noble art of aviculture. Without the bees, we would not have much in the way of fruit or vegetables. Not only would this be a disaster for human farming—just contemplate how many other creatures rely on those fruit! Similarly the ants bulwark an entire portion of the ecosystem by scavenging the tidbits out of fields and forests. Writing about the hymenoptera may be an itchy, antsy business but it is a well-merited study. This group of insects is pivotal to life on dry-land as we know it. The biblical promised land was one of milk and honey. There would be no milk without mammals, but there would be no honey (and precious few mammals) without the hymenoptera.
A beekeeper completely covered with swarming honey bees in a “bee man” cantest in China
Obdurodon--A Miocene Platypus which flourished 15 to 20 million years ago
Ferrebeekeeper has an abiding interest in monotremes including both the poisonous platypus and the enigmatic echidnas (with their advanced frontal cortex). But sadly that is about it as far as it goes for the extant egg-laying mammals: there are only two living families of monotremes (with a scanty total of five species split between them). To learn more about these animals one must turn to paleontology. Unfortunately even in the fossil record, monotremes are extremely rare.
Based on genetic evidence, biologists believe that the first monotremes made their advent in the history of life about 220 million years ago during the Triassic era; however the earliest known fossil monotreme so far discovered was a fossil jaw from the early Cretacious era about 120 million years ago. The bones belonged to Steropodon galmani, which seems to have been a beaked swimmer about 50 cm (20 inches) long which lived in Australia. Steropodon was apparently a giant among Cretacious mammals–most of which seem to have been shrew-sized (so as to better avoid attention from their contemporaries, the dinosaurs). Reconstructions of Steropodon all seem to resemble the platypus, and most paleantologists would probably concede that it was a sort of platypus—as apparently were other Mesozoic fossil monotremes such as Kollikodon and Teinolophos (platypuses and these platypus-like forbears are called the Ornithorhynchida). During the Cretaceous era, the land which is now Australia was in the South Polar regions of the world (approximately where Antarctica is today). Although temperatures were much warmer during the Cretaceous, monotremes must still have been able to deal with terrible cold: it is believed that the extremely efficient temperature control and the deep hibernation mechanism which these animals continue to display first evolved during that time.
An artist's reconstruction of Steropodon
The only monotreme fossil which was not found in Australia was from another platypus-like creature named Monotrematus sudamericanum. The creature’s remains were found in a Patagonian rock formation from the Paleocene era (the era just after the fall of the dinosaurs). Monotremes probably flourished across South America and Antarctica, as well as on Australia, but evidence is still scarce. There are most likely many interesting monotreme fossils throughout Antarctica, but, for some reason, paleontologists have not yet discovered them. Additionally, unlike the marsupials (which still quietly flourish throughout South America), the poor monotremes were wiped out on that continent.
Another artist's vision of Steropodon galmani--Notice how peeved the poor creature looks!
Last week I wrote about the Eocene era and the great proliferation of mammalian types which took place during that warm and fecund time. Although most families of mammals alive today first appeared on the scene during the Eocene, obviously the monotremes were already incredibly ancient. The Eocene does however seem to have been significant time for the monotreme order: the aquatic platypuses were apparently the ancestral monotremes, and echidnas (the Tachyglossidae) probably split off from them during the Eocene. Unfortunately we have no Eocene monotreme fossils so this conclusion is based on genetic evidence and on the suffusion of Miocene monotremes which include representatives of both Ornithorhynchida and Tachyglossidae. Some of these latter creatures are spectacular, like Zaglossus hacketti the giant echidna from the Pleistocene which was about the size of a ram! As Australia dried up so did the monotremes and now there is only one species of platypus left…
The Giant Echidna (Zaglossus hacketti) which lived until 20,000 years ago...
Well, that’s a cursory history of the monotremes based on what we know. I wish I could tell you more but unfortunately there is no fossil evidence concerning the first half of the order. Sometimes I like to imagine the first monotremes—which were probably clunky, furry platypus-looking characters with an extra hint of iguana thrown in. These creatures fished in the alien rivers of the Triassic world in a time when dinosaurs and pterosaurs were also still evolving.
ferrebeekeeper 