Gaiasia jennyae (artist's impression)
Credit: Gabriel Lio
Way back in the 99.9975% of Earth's history that occurred before creationism's legendary 'Creation Week' with its small, flat planet with a dome over it that Creationists think was the entire universe, there was something nasty lurking in the southern swamps.
It was some 300 million years before 'Creation Week' to be approximately precise and had already made it to the apex predator of its time, strongly suggesting there were other edible things roaming the same ancient swamps.
The creature, known to science as Gaiasia jennyae was a giant amphibian, a descendant of amphibians that had been extinct for 40 million years from a phylum that was to give rise to the reptiles and eventually the dinosaurs some 40 million years later.
As an amphibian, it would have been tied to water for reproduction as its eggs were fertilised externally in water and its larval form would have lived in water, probably breathing with gills, like the tadpoles of frogs, newts, toads and salamanders of today.
It's modus operandum appears to have been a slow ambush predator, laying in a swamp with its huge mouth open ready to snap up anything that came within range with interlocking jaws and the front of its mouth bristling with large, sharp teeth that gave its prey little chance of surviving. It's skull alone was over 2 feet long and the whole creature was larger than an adult human being.
Gaiasia was a stem tetrapod, in other words it was close to creatures that had evolved from Tiktaalik, the lobe-finned fish that first crawled onto land and would later evolve into the terrestrial tetrapod vertebrates, amphibians, reptiles, birds and mammals that comprise the world's larger land animals and several aquatic species that have returned to the water.
What information do you have on the Gai-as geological Formation in Namibia? The Gai-As Formation is a significant geological formation located in Namibia. Here's an overview of its key aspects:The giant salamander was discovered by Claudia Marsicano of the University of Buenos Aires and her colleagues in the Gai-as Formation in Namibia and is described by her and co-author Dr Jason Pardo, an NSF postdoctoral fellow at the Field Museum in Chicago, in a paper in Nature which is behind a paywall with only the abstract freely available. Their work is the subject of a Field Museum new release:
Geographical and Stratigraphic Context
- Location: The Gai-As Formation is situated in the northwestern part of Namibia.
- Stratigraphy: It belongs to the upper portion of the Karoo Supergroup, a major geological group in southern Africa known for its extensive sedimentary deposits.
- Age: The formation is primarily from the late Permian to early Triassic periods, dating roughly between 260 to 250 million years ago.
Lithology and Depositional Environment
- Lithology: The Gai-As Formation is characterized by its diverse sedimentary rock types, including sandstones, siltstones, and mudstones. These rocks indicate various depositional environments ranging from fluvial (river) to lacustrine (lake) settings.
- Depositional Environment: The formation's sediments were deposited in environments influenced by ancient river systems and lakes. The presence of mudstones and siltstones suggests episodes of low-energy, possibly lacustrine conditions, while sandstones indicate more dynamic fluvial processes.
Paleontological Significance
- Fossils: The Gai-As Formation is known for its fossil content, including plant fossils and vertebrate remains. The fossils provide valuable insights into the ecosystems of the late Permian to early Triassic periods in this region.
- Paleoclimate: The formation's fossils and sedimentary structures help reconstruct the paleoclimate, indicating a transition from more humid conditions in the late Permian to arid conditions in the early Triassic.
Economic and Scientific Importance
- Economic: While the primary significance of the Gai-As Formation is scientific, understanding its depositional environments and fossil content can also have implications for natural resource exploration, including hydrocarbons.
- Scientific: The formation is crucial for studying the Permian-Triassic boundary, a period marked by one of the most significant mass extinction events in Earth's history. The sedimentary records and fossils provide insights into the biotic and environmental changes during this critical transition.
Key Studies and Research
- Numerous geological and paleontological studies have been conducted on the Gai-As Formation, focusing on its stratigraphy, sedimentology, paleontology, and paleoenvironmental reconstruction. These studies contribute to the broader understanding of the Karoo Supergroup and the geological history of southern Africa.
In summary, the Gai-As Formation is a geologically and paleontologically significant formation in Namibia, providing valuable insights into the late Permian to early Triassic periods. It is characterized by diverse sedimentary deposits and fossils, which help reconstruct past environments and climatic conditions.
Giant salamander-like creature was a top predator in the ice age before the dinosaurs
Forty million years before the first dinosaurs evolved, a ferocious predator lurked in swampy waters. Its skull alone was over two feet long. It lay in wait, its jaws open wide, preparing to clamp down its interlocking jaws on any prey unwise enough to swim past. Meet Gaiasia jennyae, the swamp creature with a toilet seat-shaped head. Scientists described the newly-discovered fossil in a paper in the journal Nature.
Gaiasia jennyae was considerably larger than a person, and it probably hung out near the bottom of swamps and lakes. It's got a big, flat, toilet seat-shaped head, which allows it to open its mouth and suck in prey. It has these huge fangs, the whole front of the mouth is just giant teeth. It’s a big predator, but potentially also a relatively slow ambush predator.
Dr. Jason Pardo, co-lead author
Negaunee Integrative Research Center
Field Museum of Natural History, Chicago, IL, USA.
The fossil is named for the Gai-as Formation in Namibia where it was found, and for Jenny Clack, a paleontologist who specialized in the evolution of early tetrapods-- the four-limbed vertebrates that evolved from lobe-finned fishes and gave rise to amphibians, reptiles, birds, and mammals.
When we found this enormous specimen just lying on the outcrop as a giant concretion, it was really shocking. I knew just from seeing it that it was something completely different. We were all very excited. After examining the skull, the structure of the front of the skull caught my attention. It was the only clearly visible part at that time, and it showed very unusually interlocking large fangs, creating a unique bite for early tetrapods.
Claudia Marsicano, co-lead author
Departamento de Cs. Geológicas
Faculty of Exact and Natural Sciences Universidad de Buenos Aires, Buenos Aires, Argentina.
The team unearthed several specimens, including one with a well-preserved, articulated skull and spine.
We had some really fantastic material, including a complete skull, that we could then use to compare with other animals from this age and get a sense of what this animal was and what makes it unique.
Dr. Jason Pardo.
It turns out, there’s a lot about the creature that makes it special.
While today, Namibia is just north of South Africa, it was even further south 300 million years ago. It was near the 60th parallel, almost even with the northernmost point of Antarctica today. And at that time, the Earth was nearing the end of an ice age. The swampy land near the equator was drying up and becoming more forested, but closer to the poles, the swamps remained, potentially alongside patches of ice and glaciers.
In the warmer, drier parts of the world, animals were evolving to new forms. Early four-legged vertebrates, called stem tetrapods, branched out and split into lineages that would one day become mammals, reptiles, and amphibians. But on the fringes, in places like what’s now Namibia, more ancient forms remained.
Gaiasia is a stem tetrapod-- it’s a holdover from that earlier group, before they evolved and split into the groups that would become mammals and birds and reptiles and amphibians, which are called crown tetrapods. It’s really, really surprising that Gaiasia is so archaic. It was related to organisms that went extinct probably 40 million years prior.
Dr. Jason Pardo.
What’s more, for an oddball holdover from an even more ancient time, Gaiasia seemed to be doing pretty well for itself.
“There are some other more archaic animals still hanging on 300 million years ago, but they were rare, they were small, and they were doing their own thing. Gaiasia is big, and it is abundant, and it seems to be the primary predator in its ecosystem.
Dr. Jason Pardo.
And while Gaiasia jennyae is just one species, it yields big-picture information for paleontologists studying how the world was changing during the Permian period.It tells us that what was happening in the far south was very different from what was happening at the Equator. And that’s really important because there were a lot of groups of animals that appeared at this time that we don’t really know where they came from. The fact that we found Gaiasia in the far south tells us that there was a flourishing ecosystem that could support these very large predators. The more we look, we might find more answers about these major animal groups that we care about, like the ancestors of mammals and modern reptiles.
Dr. Jason Pardo.
Abstract Current hypotheses of early tetrapod evolution posit close ecological and biogeographic ties to the extensive coal-producing wetlands of the Carboniferous palaeoequator with rapid replacement of archaic tetrapod groups by relatives of modern amniotes and lissamphibians in the late Carboniferous (about 307 million years ago). These hypotheses draw on a tetrapod fossil record that is almost entirely restricted to palaeoequatorial Pangea (Laurussia)1,2. Here we describe a new giant stem tetrapod, Gaiasia jennyae, from high-palaeolatitude (about 55° S) early Permian-aged (about 280 million years ago) deposits in Namibia that challenges this scenario. Gaiasia is represented by several large, semi-articulated skeletons characterized by a weakly ossified skull with a loosely articulated palate dominated by a broad diamond-shaped parasphenoid, a posteriorly projecting occiput, and enlarged, interlocking dentary and coronoid fangs. Phylogenetic analysis resolves Gaiasia within the tetrapod stem group as the sister taxon of the Carboniferous Colosteidae from Euramerica. Gaiasia is larger than all previously described digited stem tetrapods and provides evidence that continental tetrapods were well established in the cold-temperate latitudes of Gondwana during the final phases of the Carboniferous–Permian deglaciation. This points to a more global distribution of continental tetrapods during the Carboniferous–Permian transition and indicates that previous hypotheses of global tetrapod faunal turnover and dispersal at this time2,3 must be reconsidered.
Marsicano, C.A., Pardo, J.D., Smith, R.M.H. et al. Giant stem tetrapod was apex predator in Gondwanan late Palaeozoic ice age. Nature (2024). https://doi.org/10.1038/s41586-024-07572-0
© 2024 Springer Nature Ltd.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
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