Rosa Rubicondior: Creationism Refuted - A Massive Evolutionary Arms Race 130 Million Years Before 'Creation Week'

Illustration of some of the apex predators in the Paja Formation biota with a human for scale.

Image by Artwork by Guillermo Torres, Hace Tiempo, Instituto von Humboldt.

Apex predators in prehistoric Colombian oceans would have snacked on killer whales today: McGill study | Newsroom - McGill University

Two researchers at McGill University, Montréal, Québec, Canada, have uncovered evidence of an ecosystem teeming with giant marine predators some 130 million years ago. The largest of these predators could, quite literally, have eaten something the size of a modern orca as little more than a snack. This will make depressing reading for creationists, not only because it all happened deep in the long pre-“Creation Week” history of life on Earth, but because the evolutionary arms races that led to these giants are precisely what the theory of evolution by natural selection predicts.

The two researchers, Dirley Cortés and Professor Hans C. E. Larsson, have just published their findings, open access, in the Zoological Journal of the Linnean Society.

It doesn’t get any easier for creationists. Just because it’s Christmas week doesn’t mean the awkward facts are going to go away, or that scientists are going to stop uncovering more of them. No matter what they post on social media; no matter how loudly they shout; or how fervently they gather on Sundays to collectively drown out their doubts, Santa is not going to deliver evidence that the Bronze Age creation myths in the Bible contain even a grain of historical truth. The problem is that truth remains true whether a creationist believes it or not, and regardless of whether their parents believed it. No amount of looking the other way or pretending the facts aren’t there will ever change that.

The palaeontologists reached their conclusions by reconstructing an ecosystem network for all known animal fossils from the Paja Formation in central Colombia. They used body sizes, feeding adaptations, and comparisons with modern animals, and then validated the results against one of the most detailed present-day marine ecosystem networks available: the living Caribbean ecosystem, which they used as a reference. The Paja ecosystem thrived with plesiosaurs, ichthyosaurs, and abundant invertebrates, giving rise to one of the most intricate marine food webs known. This complexity emerged as sea levels rose and Earth’s climate warmed during the Mesozoic era, including the Cretaceous, triggering an explosion of marine biodiversity.

Background^ The Paja Ecosystem (Colombia). The Paja Formation is a Lower Cretaceous geological formation exposed in central Colombia, particularly within the Eastern Cordillera. It represents a shallow to moderately deep marine environment that existed along the northern margin of South America when the region was covered by warm epicontinental seas.

The Paja ecosystem flourished during the Early Cretaceous, roughly 130–115 million years ago, spanning the Barremian to early Aptian stages. At the time, rising sea levels and a greenhouse climate created conditions highly favourable to marine life, leading to complex and productive food webs. Fossils recovered from the Paja Formation include an exceptionally rich assemblage of marine reptiles, notably large plesiosaurs and ichthyosaurs, alongside sharks, bony fishes, ammonites, belemnites, crustaceans, and other invertebrates. The presence of multiple large apex predators indicates a well-structured ecosystem with sufficient primary productivity to support high trophic levels—something only stable, long-lived marine systems can achieve.

How the Paja Formation Is Dated

The age of the Paja Formation is established using several independent and mutually reinforcing dating methods, rather than relying on a single technique:

Biostratigraphy
The primary dating method uses index fossils, especially ammonites, which evolved rapidly and had wide geographic distributions. Specific ammonite species found within the Paja Formation correspond closely to well-dated Barremian and Aptian stages elsewhere in the world.
Lithostratigraphic correlation
The rock layers of the Paja Formation can be matched with contemporaneous marine deposits in other parts of South America and globally, based on sediment type, layering, and fossil content.
Radiometric dating of associated volcanic material
While the Paja Formation itself is largely sedimentary, nearby volcanic ash layers and igneous intrusions of known age help constrain the timing of deposition through radiometric methods such as uranium–lead and argon–argon dating.
Chemostratigraphy and palaeoenvironmental markers
Global geochemical signals—such as carbon isotope excursions associated with Early Cretaceous oceanic anoxic events—provide additional chronological anchors that align the Paja deposits with well-dated global climate events.

Together, these methods place the Paja ecosystem firmly within the Early Cretaceous, long before the appearance of modern marine mammals and vastly predating any human history.

More details of the study are given in a McGill University news item.

Apex predators in prehistoric Colombian oceans would have snacked on killer whales today: McGill study
Researchers uncovered a prehistoric ecosystem teeming with giant marine reptiles, uncovering unmatched food web complexity
Predators at the top of a marine food chain 130 million years ago ruled with more power than any modern species, McGill research into a marine ecosystem from the Cretaceous period revealed.

The study, published in the Zoological Journal of the Linnean Society, reconstructs the ecosystem of Colombia’s Paja Formation, and finds it was teeming with marine reptiles reaching over 10 metres in length that inhabited a seventh trophic level.

Trophic levels are the layers or ranks within a food chain that describe the roles organisms play in an ecosystem based on their source of energy and nutrients. Essentially, they help define who eats whom in an ecosystem. Today’s marine trophic levels cap at six, with creatures like killer whales and great white sharks.

The discovery of giant marine reptile apex predators occupying a seventh trophic level underscores the Paja ecosystem’s unmatched diversity and complexity, offering a rare view into an evolutionary arms race among predators and prey.

In their study, McGill researchers reconstructed an ancient ecosystem network for all known animal fossils in a single geological formation in central Colombia. This network was constructed using body sizes, feeding adaptations and analogues to animals living today. They also checked their network against one of the most detailed present-day marine ecosystem networks, based on living Caribbean ecosystems, which they had used as a reference.

The Mesozoic era, which included the Cretaceous period, was marked by rising sea levels and warmer climates, leading to an explosion of biodiversity in marine life. The Paja ecosystem thrived with plesiosaurs, ichthyosaurs, and abundant invertebrates, giving rise to one of history’s most intricate marine food webs.

Our study is the first to examine these possible ecological interactions. Understanding this complexity helps us trace how ecosystems evolve over time, shedding light on the structures that support today’s biodiversity.

Dirley Cortés, lead author.
Redpath Museum, Biology Department
McGill University
Montréal, Québec, Canada.

These findings illuminate how marine ecosystems developed through intense trophic competition and shaped the diversity we see today.

Professor Hans Larsson, co-author.
Redpath Museum, Biology Department
McGill University
Montréal, Québec, Canada.

This research is just the beginning, the researchers said, as few fossil ecosystems have had their food webs reconstructed. There is potential for new comparisons across time and space, advancing our understanding of ancient marine life and its impact on today’s oceans.

Publication:
Dirley Cortés, Hans C E Larsson
Top of the food chains: an ecological network of the marine Paja Formation biota from the Early Cretaceous of Colombia reveals the highest trophic levels ever estimated
Zoological Journal of the Linnean Society, 202(1), September 2024, zlad092, https://doi.org/10.1093/zoolinnean/zlad092

Studies like this are not isolated curiosities, nor are they awkward anomalies that can be brushed aside with a shrug. They are part of a vast and internally consistent body of evidence showing how ecosystems emerge, diversify, and stabilise over immense spans of geological time. The Paja marine ecosystem was not a chaotic free-for-all, but a structured, energy-rich system capable of supporting multiple layers of large apex predators—exactly what evolutionary theory predicts when ecological opportunity and time are allowed to do their work.

For those prepared to engage with the evidence, this research offers a glimpse into a long-vanished world whose complexity rivals that of modern oceans. For those who insist that the Earth’s history must fit inside a few thousand years and a literalist reading of ancient myth, it presents yet another immovable problem. Fossils do not negotiate, rock layers do not lie, and nature does not bend to theology. The Paja ecosystem existed, it evolved, and it left a record that we can still read today—whether or not anyone is comfortable with what it says.

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