The Carboniferous Earth s Time of Giants and Swamps Prehistoric Documentary

From 358 to 298 million years ago, the world was in an age drastically different to the one we find ourselves in today. Nestled in the Paleozoic era between the late Devonian and the early Permian, the Carboniferous was a world characterized by humid, tropical coal forests that sprouted up across much of the world. These colossal swathes of tree ferns were nearly endless, and within them life was truly beginning to develop. Terrestrial animals were firmly established by the time the Carboniferous was in full swing. Tetrapods were among the most dominant animals on the land, and strange, otherworldly fishes thrived in the vast global ocean. On land, however, one group of animals, due to the increased levels of oxygen in the Earth's atmosphere, drew to immense sizes. The terrestrial arthropods. Insects, millipedes and their relatives were at the largest they have ever been before or since in the Carboniferous, and they continue to instill fear and awe into the minds of paleontology enthusiasts today. Join us as we trudge through these sweltering swamp forests in search of some of the strangest animals that have ever walked the Earth. Welcome to the Carboniferous period. The seas of endless green that made up the ancient swamp forests of the Carboniferous are responsible for many of the coal fields and deposits in the modern world. But how could that have happened on such a notable scale? Well, while the highlands of this verdant world were atmospherically dry, the lowlands were hot, humid and covered in swampy ground. Rivers flowed from the highlands to the lowlands and flooded these forests, which forced the ground into a dense, marshy wetland. Many of these swamps were composed of small, stagnant pools amidst the boggy Earth, but some were large enough to form lakes. Many of them would have been obscured by leaf litter and mud, making visibility for aquatic life very low. That leaf litter would have accumulated over time, where, due to the lack of oxygen in the bog, it did not fully decompose. As such, thick layers of partly decomposed plant matter formed over time, known today as peat. These layers of peat became buried by sediment as the millennia passed, where it turned into lignite and then into coal. This coal is mine today, and all of it can be traced back to these mighty forests. The forests themselves would not have closely resembled those we see today. While today, flowering trees or evergreen firs compose many of our woodlands, the Carboniferous swamp forests would have been dominated by lycopods, tree ferns and horsetail-like plants. The most famous genus of Carboniferous tree was Lepidodendrum, a type of primitive lycopod that is very well preserved in the fossil record. Some specimens of Lepidodendrum could reach 50 meters or 160 feet tall, and their trunks often exceeded a meter or three feet in diameter. The trunks of these towering colossi would have been largely branchless, save for the canopy where multiple dense, fern-like arms sprouted from the very tallest points. Lepidodendrum's unique scale-like trunk coverings are very well preserved in the fossil record, forming diamond-shaped lattices across the entire wooded exterior. Other lycopods, such as Sigillaria, sprouted into two distinct tufts of ferns at the canopy, and grew slightly smaller, reaching heights of 30 meters or 98 feet tall. At the ground level, a multitude of fern-like bushes and shrubs would have formed dense thickets and undergrowths. This would be perfect for animals, both vertebrate and arthropod, to conceal themselves. So dense and widespread were these forests, that the oxygen content on Earth reached levels of 35%. For reference, we are at 21% today. It's these heightened oxygen levels that led to some of the evolutionary oddities we will be meeting shortly. The Carboniferous Period's rainforests unfortunately did not last forever. Glaciations at the end of this period resulted in the lowering of the global sea level as the world drifted into the early Permian. This is known as the Carboniferous Rainforest Collapse, and it saw enormous swathes of these swampy woodlands recede. In the Permian, the world would become drier, characterized by arid plains, deserts, and mountains, as the continents collided to form Pangaea. Many of the giant insects and other arthropods would not be able to cope with this change, and although a handful persisted, the world would never again meet such giants. So let's press on through this endlessly wooded world, from the swamps to the seas, to meet the animals that dwelled within. We will examine the Carboniferous' most characteristic and unusual residents closely, species by species, coming face to face with some of the most extreme examples of Paleozoic evolution in the fossil record. Let's hope you're not too scared of a few bugs. For many, Meganeura monii, a species of giant griffinfly that closely resembled the modern dragonfly, defines the Carboniferous period. Darting across the wider lakes of the swamp forests that would one day become Europe, Meganeura was an efficient predator. Like the modern dragonfly, especially hawkers, it snatched prey while flying by flitting over the water's surface, using its spiny legs as a trap to ensnare prey. Unlike modern dragonflies, however, it was the size of a small hawk. Those increased oxygen levels, combined with the fact that Meganeura had no aerial predators to worry about, meant that this insect could reach gigantic proportions. Wingspans of 70cm or 27.5in were not unheard of. For reference, the world's largest modern dragonfly, the giant petaltail, has a wingspan of just 16cm or a little over 6in. That's more than 20in smaller. Meganeura's fossils were first unearthed in France from, as you might guess, a coal mine. Described in 1884, French paleontologist Charles Brognard was quick to impeccably preserve wing imprints in the sediment in which the huge bug was found. It was recognized not as a dragonfly, but as a member of the now entirely extinct order Meganeisoptera, and placed in its own family, Meganeuridae. While Meganeura had adapted to living within the swampy coal forests, it specifically seems to have been suited to open environments within them, such as lakes, where its wings would not be damaged upon contact with the dense vegetation, and where a reliable source of food was available. This insect is thought to have taken both vertebrates and invertebrates as prey, being large enough to prey upon some of the small early reptiles that darted in and out of view along the It is thought that despite the fact it was adapted to living in very humid conditions, Meganeura could overheat if it spent too much time hunting on the wing, and so it needed to take regular breaks to cool itself down and rest. During this time, it would have been vulnerable to predation itself from some of the larger vertebrate denizens of the lake, and as such, it may have attempted to perch on higher ground where it didn't become a meal itself. Sadly, as the coal forests retreated, Meganeura would not be able to cope with the drying of its world, especially when the swamps started to disappear. Meganeura, and many of the other large insects it lived with, found themselves dying out, their remains becoming features of the coal that lay beneath the very lakes over which they hunted. If Meganeura seemed too big for an arthropod, you might want to proceed with caution when we meet this next swamp forest inhabitant. Arthropleura armata, another famous figurehead of the Carboniferous, may well have been the largest terrestrial arthropod ever to walk the earth. Capable of reaching at least 2 meters, or 6 foot and 7 inches in length, this behemoth of the forest floor was a huge myriapod, a relative of the modern-day centipedes and millipedes. Fossils of Arthropleura have been found in Europe and North America, in the form of both fossilized body segments and the giant trackways it left behind as it walked through the undergrowth, its many, many legs visible in the rock. Like all myriapods, Arthropleura's body was segmented, with broad carapace covering its head and legs. That head was tipped with a pair of sharp cutting jaws, which would have given it a fearsome appearance in life. Despite this appearance however, Arthropleura was a strict herbivore. Its gut content has been discovered in partially well-preserved fossils, which show this huge arthropod was feasting on woody plants and leafy detritus before it had died. Combining this with the location of the fossil trackways attributed to the species would suggest that it preferred open stretches of woodland adjacent to water. New evidence even suggests that it was comfortable entering the water, living a semi-aquatic lifestyle. Trackways of the Arthropleura have been unearthed in aquatic deposits as well as terrestrial ones, indicating that when the animal entered the water it would have crawled along the bottom, perhaps picking up decaying leaves as it wandered from A to B. Many of the known fossils for Arthropleura come in the form of molted shells, rather than the animal's actual carcass. Seasonally, Arthropleura would have entered the water to perform a molt, a time when it was at its most vulnerable. When the arthropod outgrew its carapace, it would have been shed, meaning that until the newly grown one had hardened, a soft, fleshy body would be left underneath. The animal would also be physically weaker at this time, with the carapace providing strong support to Arthropleura's body when walking. It is for this reason that molts are believed to have taken place underwater, where it essentially could live more like a worm than a centipede, until it was back to its strong self once again. When in this vulnerable state, it may have also burrowed into the trunks of the towering lycopod trees, helping it to stay humid and protected from external threats. In the murk of the swamps that littered the European Carboniferous forest floor lived an unseen threat. Growing two meters or six and a half feet from nose to tail, Crassigyrinus scoticus was an underwater ambush predator, and an unusual one at that. With a tapering, streamlined body and a paddled tail that resembled that of a tadpole, Crassigyrinus was a basal tetrapod that resembled a gigantic salamander, but one that could not leave the confines of the water. Even if it wanted to do so, its limbs were tiny and vestigial, used only for basic steering movement in the water. So tiny were its limbs that paleontologists once thought it may have lost them throughout the course of its evolution. But as there is evidence of healed limb injuries in some Crassigyrinus specimens, they must have been used for something. What was most impressive about this skulking freshwater carnivore was its skull. In life, the animal's visage would have resembled an odd mix of newt, moray eel and crocodile, and the jaws were particularly massive. Sharp teeth adorned every inch of the jaw, with large palatal fangs present on the second row. These teeth would have been used to snap up the various species of fish and aquatic tetrapod that shared the swamps with Crassigyrinus, and it may have been able to open its mouth up to 60 degrees wide to fit larger animals in its mouth. When it needed to, Crassigyrinus could really move, and it likely used the low visibility of its murky home to its advantage. Hiding in the gloom, it could get close to its prey, before darting into action, teeth first. Further supporting the ambush predator theory, Crassigyrinus' eyes were very large, helping it to see where others could not. Despite the fact that Crassigyrinus is a relatively well understood animal, scientists have had a hard time placing it reliably in the tetrapod family tree. It currently sits in its own family, Crassigyrinidae, but its features, reminiscent of both fish and tetrapods, have, over the years, thrown researchers off the mark. There are some who initially thought it was a labyrinthodont, a taxonomically informal group of amphibian-like animals, which does little to firmly place Crassigyrinus in a group. What is clear, however, is that the animal is very basal, and while it probably is a tetrapod given the presence of vestigial limbs, some scientists don't actually consider it to be one. Whatever its placement in the fossil record, Crassigyrinus was one of the first truly deadly tetrapods in the fossil record, a pioneer of the aquatic ambush predator niche that would see such great success in the future. Hauling itself up from the stagnant swamps and ambling slowly along the water's edge, now comes Hippotopterus, a bizarre arthropod resembling, in part, a modern horseshoe crab. Heavily armored with a shield-like head and a segmented trailing body, Hippotopterus was a eurypterid, a relative of the colloquially named sea scorpions that were so successful in the Ordovician and Silurian periods. The largest species of the genus are almost a meter and a half or four and a half feet in length, and were found across Europe, North America, and Africa. Hippotopterus' forward-facing set of limbs would have been covered with modified spines, each of which was tipped with sensory organs for detecting food along the bottom of murky swamps and lakes. These limbs would have been used effectively as rakes, sifting through the leaf litter and detritus at the bottom of the water to obtain small invertebrates in large numbers. This is a very specialized form of feeding, and one which initially led scientists to believe that this was an ocean-going animal, yet it was indeed found in the swampy Lepidodendron forests that also harbored the likes of Arthropleura. Once food had been obtained, it would have been brought up to Hippotopterus' small and surprisingly weak mouthparts. The lack of strength in these structures indicates that the animal could not have killed and eaten larger animals, but it was suited to the many soft-bodied mollusc-like animals that thrived amongst the watery leaf litter. Like Arthropleura, there are known Hippotopterus tracks in what is today Scotland. For roughly 6 meters at least, there is evidence that a lone, meter-and-a-half-long Hippotopterus crawled out slowly of the muddy waters of what is today Fife and crept along the water's edge. When out of the water, it wasn't a graceful animal by any means. The tracks are clunky and disorganized, and it may have been dragging most of its body along as the front limbs did all the work. This was an animal with gills, and so it likely spent the vast majority of its time feeding or resting under the water, but we now know that it was also able to head onto land, if only for a short while. It could still breathe as long as its gills remained wet, but some Eurypterids may have had a dual respiratory system made up of both lungs and gills, meaning that they could breathe on land as well as underwater. It is not known if Hippotopterus was one of these, however. Perhaps Hippotopterus ventured onto land to escape danger, to travel from pool to pool, or to search for different sources of food that were not available underneath the swampy surface. For a 380 million-year-old reptile, Hylonimus looks extremely familiar. This little lizard-like animal measures no longer than 25 centimeters, or around 10 inches. It is the oldest known objective reptile in the fossil record. Its very existence kick-started one of the most awesome dynasties in the entire animal kingdom. Since its discovery in 1860, it has remained a beacon of interest on how vertebrates were able to transition from a semi-aquatic lifestyle to one spent entirely on land. The secret to Hylonimus' success was in its skin. Unlike that of an amphibian or a basal tetrapod, who possess slimy skin, this little reptile was covered in tough scales. Scales protected its skin and prevented it from drying out. No longer did Hylonimus need to take a dip to stop itself from drying out. It could reliably live outside of a lake or river for an extended period of time. Of course, it still needed access to water to drink, but this was a massive step forward. This terrestrial adaptation was twofold however. Not only was Hylonimus' skin scaly, but its eggs were covered in a hard shell, protecting them from drying out too. This meant that unlike the frog-spawn-like eggs laid by amphibians, Hylonimus didn't need to lay its eggs in water. Therefore, it protected them from hungry fish. By laying its eggs in a safe, protective cavity or nest, these new types of egg would be the norm for all future reptiles, dinosaurs, and birds. Hylonimus would have spent much of its time darting through the forest floor in search of small arthropods. It was likely a lover of insects and myriapods. With a mouth full of sharp, needle-like teeth, it would have effortlessly smashed through the tough carapaces to feed on the soft insides. It is most closely associated with the Joggins Formation in what is now Nova Scotia, Canada, where it has become the official provincial fossil. Often the remains of Hylonimus were found under rather brutal circumstances. Across much of the Joggins Formation, club mosses forming giant tree-like structures were dominant plant species. Dense tropical forests were known for their poor weather, and when storms battered the swamps, the club mosses would fall to the ground, exposing just a stump. With time, the stumps would rot away, leaving hollow cavities in the middle, perfect shelter or so it would seem for a small animal such as the Hylonimus. When the next storm inevitably came along, Hylonimus would crawl into the stump cavity of the previously fallen trees. Once inside, however, it would not be able to scale the steep, slippery sides of the cavity again, and it would become trapped, ultimately dying from starvation. The most dangerous denizen of the Carboniferous Swamp Forests was not an arthropod, an amphibian, or even a reptile. It was a giant fish, one capable of reaching sizes in excess of 5.5 meters or 18.5 feet in length. This fish, Rhizodus hiberti, is one of the most fearsome Piscine apex predators in the fossil record. With powerful lobed fins and a set of long, snapping jaws, it would have been safe as the aquatic ruler of the swampy ecosystems. Rhizodus was a resident of broad lakes and rivers under the canopies of giant tree ferns, where it could feed on amphibians, fish, and other tetrapods. Two fangs, 22 centimeters in length, situated near the front of its jaws would have short work of most prey items in these rivers, with fully grown adults fearing nothing except perhaps another Rhizodus. Fully grown adult Rhizodus are theorized to have exceeded weights of one and a half tons. Some scientists have proposed that Rhizodus adopted a particularly terrifying hunting method. Using its powerful lobed pectoral fins, it may have been able to launch itself out of the riverbank, launching at prey like a modern crocodile. In this way, very few animals of the Carboniferous swamps would be safe as they approached the edge of the water to drink, and would have needed to be on high alert when doing so. Once the prey was firmly encased in Rhizodus' massive jaws, it would have used its immense body muscles to drag it back into the water to begin feeding. When feeding, it is thought that Rhizodus would have used its sharp teeth to tear the animal into digestible sizes. It was incapable of chewing, and could not have swallowed prey whole. By far the most bizarre species featured in today's video is Tullamonstrum gregarium, a strange animal known from the Maison Creek fossil beds in what is today Illinois in the United States. Tullamonstrum is one of the biggest enigmas in all of paleontology, and scientists, since its initial description in 1966, have not been able to pin down this creature's place in the tree of life. Over the years it has been considered to be a mollusk, an arthropod, a worm, a vertebrate and a conodont. So what makes it so odd? Tullamonstrum had a tubular, cigar-shaped body, and measured no longer than 8cm or 3 inches from the tip of its snout to the end of its tail. A pair of fins ran along the flanks of its tail in a triangular shape, which would have helped it swim through the shallow estuaries and lakes during its life. Tullamonstrum's mobile eyes were set on stalks, allowing it to see in the water column, where it was thought to have been a predator. It likely hunted using the most unusual feature of its body, a long proboscis tipped with a pincer structure at its end, which may have actually been its mouth. Scientists believe that Tullamonstrum would have used this pincer to probe muddy sediments for small animals to eat. It is unknown whether Tullamonstrum was in possession of a true spine, but it seems to have had a basic spinal cord running along the length of its body, alluding to some form of relationship with vertebrates. Structures at the base of its head have been identified as basic gills, meaning it would have led its whole life submerged underwater. Despite the fact that the two don't appear to be related in any way, Tullamonstrum bears some similarities with the invertebrate Opabinia, given its stalked eyes and long, probing snout. It's highly unusual, then, that it appears in Carboniferous Age rocks, considering that nothing else like it exists around the same time. It shared the estuaries of ancient Illinois with cephalopods, horseshoe crabs, cartilaginous fishes, eurypterids, and sea anemones. But nothing even begins to come close to Tullamonstrum. To signify its importance to the natural history of Illinois, it was designated as its official state fossil in 1989, and some U-Haul rental cars from the region still picture the creature today. In central Montana, rocks dated to around 324 million years ago denote one of the most fascinating ecosystems of the Carboniferous, and they're a far cry from the murky swamp forests we typically associate with the period. This is the Bear Gulch limestone, which in the Carboniferous would have been brackish coastline, subtropical with distinct wet and dry seasons. Amidst the rocky outcrops and sandy sediments of the shallow sea were fish. Thousands upon thousands of fish, from which over 150 species are known to science in the form of extremely well-preserved fossils today. The fish at Bear Gulch are truly bizarre, and many of them are chondrichthyans, cartilaginous fishes related to sharks, rays, and chimeras. A short dive into the waters of Bear Gulch would have yielded enough unusual cartilaginous fish to last you a lifetime. The most obtrusive of these would have been Stethacanthus productus, a shark-like animal measuring 3 meters or just under 10 feet in length. It would have resembled a typical modern shark for the most part, save for a very unusual dorsal fin. Rather than the basic triangle shape seen in today's sharks, Stethacanthus' dorsal fin was shaped like a blacksmith's anvil and was covered in sharp, spiky denticles along the top surface. These structures may have been useful to the fish when mating, or may have helped them clamp onto other animals like a modern remora. Dive a little deeper, however, and things start to get even stranger. Harpagophutator, a cartilaginous fish that resembled both an eel and a lungfish, hunted for shellfish amongst the rocky structures of the seafloor, using broad toothplates to crush them, obtaining the soft meat within. One look at these fish, however, and you'll notice something extremely odd. Atop the heads of male Harpagophutator grew long, forked antler-like structures, capable of rotating on a ball-and-socket joint against the animal's skull. No other fish is known to have had these structures in the fossil record, and given their lack in females, it would seem that they served as elaborate display features or mating aids. Female Harpagophutator are thought to have given birth to live young that were only slightly smaller than adults, large and ready to fend for themselves. However, Harpagophutator was the ideal prey for some of the more sinister denizens of the Bear Creek Rocks. Animals such as Thrinocodus were a constant threat. This long, tapering, snake-like predator, another cartilaginous fish, has been discovered with Harpagophutator remains in its stomach. Its teeth, cusped with three points, would have inflicted powerful bites upon its prey, while its long, serpentine body helped it weave in and out of rock faces in search of food in hard-to-reach places. Cartilaginous fishes took on all forms, shapes and sizes during this time, and at the very bottom of Bear Gulch would have lived creatures such as Balansi. At just over a meter in length, Balansi resembled a large frogfish and would have spent much of its time walking along the seafloor in search of fish and shellfish dwelling within the sediment. It was not a fast-moving animal, and its teeth come together to form a beak-like structure within the mouth that could have cracked into the hard shells of Bryozoans amongst the reefs and rock faces. Also searching for food along the seafloor were animals such as Janasa, a small, ray-like fish that would have hunted small, soft-bodied organisms amongst the sand. Cartilaginous fishes weren't the only species here though, and in the water column would have swum thousands upon thousands of ray-finned bony fishes, shoaling together for safety in numbers against animals such as Stethacanthus and Thrinocodus. Some would have resembled sardines and mackerel, while others took on a sinuous eel form or flattened, ray-like appearances. Others, such as Acanthodes, would have resembled the placoderms that were so successful in the Devonian, while animals such as Strepsodus represented the Rhizodonts, smaller genera related to the mighty Rhizodus that we met earlier in today's video. On the seafloor, providing sustenance to numerous fish species, were a plethora of bizarre invertebrates resembling shrimps, horseshoe crabs, lobsters, and more. Worms dug through the sand while cephalopods darted overhead. Bear Creek is, to this date, one of the most prolific and fascinating fossil sites of the entire Paleozoic, let alone the Carboniferous. It's hard to imagine a world like the Carboniferous when we live in the age we do today. Some sections of this green swampy world really did resemble alien planets, teeming with oversized arthropods, gigantic amphibious swamp monsters, and armored sea scorpions. It is a time in Earth's history that saw a great explosion of life on land, and we likely have only scratched the surface. Just think about how biodiverse and populous today's tropical forests can be. Thousands of species occupy, say, the Amazon rainforest, and we're still discovering more and more as time goes on. What would a near-global rainforest have harbored that we're missing? All we can do is to wait and see just what we discover next.