Rosa Rubicondior: Refuting Creationism - North America's Oldest Pterosaur - From 200 Million Years Before 'Creation Week'

Reconstruction of life in Arizona, 200 million years ago.

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A Bone Bed From the Dawn of the Dinosaurs Has Revealed the Oldest Known Pterosaur Found in North America

Arizona’s Petrified Forest National Park is a place that many creationists might prefer to ignore—or misrepresent. It offers a vivid record of how life changed during the Triassic Period, between 252 and 201 million years ago. In other words, it documents the history of life in what is now Arizona during the vast stretch of time that predates the so-called “Creation Week,” as described in Bible-based creationist mythology.

In addition to the petrified remains of ancient conifers, the site preserves fossils of long-extinct crocodile-like reptiles and some of the earliest dinosaurs known from North America. Now, a new study of a fossil-rich bone bed from the late Triassic—around 09 million years ago—has revealed new insights into stream ecosystems of that time, including the discovery of the largest pterosaur yet found in North America.

What information do you have on Arizona’s Petrified Forest National Park and its geology? Petrified Forest National Park, located in northeastern Arizona, is a geologically and palaeontologically significant site renowned for its vast deposits of fossilised wood and rich record of Late Triassic life. Here's an overview of its geology, palaeontology, and scientific significance:

Overview

Location: Navajo and Apache Counties, northeastern Arizona, USA.
Size: Approximately 346 square miles (900 km²).
Designation: National Monument in 1906, National Park in 1962.
Climate: Semi-arid desert; hot summers, cold winters, and low rainfall.

Geology

Chinle Formation

The dominant rock unit in the park is the Chinle Formation, a colourful sequence of sedimentary rocks laid down during the Late Triassic Period (approx. 227 to 201 million years ago).
Composed primarily of mudstone, siltstone, sandstone, shale, and volcanic ash.
Rich in iron and manganese, which contribute to the vivid bands of red, purple, yellow, and white in the so-called Painted Desert region.

Stratigraphy

Key members of the Chinle Formation exposed in the park include:

Blue Mesa Member: Soft mudstones, rich in clay; hosts many of the petrified logs.
Sonsela Member: Sandstone-dominated; contains large, well-preserved petrified trees.
Petrified Forest Member: Multicoloured mudstones; yields fossils of plants and vertebrates.
Owl Rock and Rock Point Members: Uppermost units; represent shifting fluvial and lacustrine environments.
These sediments were laid down in an environment of meandering rivers, floodplains, swamps, and lakes, within a subtropical climate at the time.

Fossilised Wood

The park is named for its abundant petrified logs, primarily of extinct conifer species such as Araucarioxylon arizonicum.
These trees were buried by volcanic ash and sediments, which halted decay and allowed silica-rich groundwater to permeate the wood, replacing organic material with quartz crystals over millions of years.
The resulting logs are often multicoloured due to trace elements (iron, carbon, manganese).

Palaeontology

Petrified Forest National Park preserves one of the most diverse Late Triassic fossil assemblages in the world:

Fauna

Phytosaurs: Crocodile-like archosauriforms.
Aetosaurs: Armoured herbivorous archosaurs.
Rauisuchians: Large predatory archosaurs.
Early dinosaurs: Including Chindesaurus, one of the earliest known theropods in North America.
Pterosaurs: Recently discovered specimens include the oldest and largest known pterosaur from North America (~209 million years old).
Metoposaurs: Large amphibians resembling giant salamanders.
Early mammals and relatives: Including cynodonts and tritylodonts.

Flora

Dominated by extinct conifers, cycads, ferns, and seed ferns—plants typical of Triassic river systems.
Fossils include leaves, cones, and wood.

Scientific Importance

Provides insight into ecosystems just before the rise of the dinosaurs to dominance.
Represents the transition from a world dominated by early archosaurs and amphibians to one where dinosaurs and pterosaurs began to flourish.
Offers evidence for climatic and ecological changes during the Triassic, including periodic mass extinctions and faunal turnovers.
A key site in the study of Triassic terrestrial vertebrate biostratigraphy and palaeoecology.

Creationist Objections

Because the park’s strata and fossil record clearly span tens of millions of years—and because its fossils show a clear evolutionary sequence — young Earth creationists often ignore or misrepresent it. They may falsely attribute the petrified wood to the biblical flood, ignoring the fine stratigraphy, radiometric dating, and fossil succession that contradict such claims.

The study was led by Ben Kligman, a palaeontologist with the Smithsonian National Museum of Natural History, and colleagues. Their findings are published in the Proceedings of the National Academy of Sciences and are discussed in a Smithsonian Magazine article by Riley Black.

A Bone Bed From the Dawn of the Dinosaurs Has Revealed the Oldest Known Pterosaur Found in North America
Fossil surprises abound in new research that unearths the history of the Triassic Period
The painted desert of Arizona’s Petrified Forest National Park is a fossil wonderland. Scattered through the sunbeaten rock are rainbow-colored trunks of prehistoric conifers, the crumbling bones of crocodile-like reptiles that lurked in ancient streams and the remnants of some of North America’s oldest dinosaurs. Together the incredible wealth of fossil sites documents how life changed through the Triassic Period, between 201 million and 252 million years ago, in the Four Corners region. Now, in a new study, a bone bed from near the end of the period has revealed a detailed look at the life that was thriving in streams and channels around 209 million years ago, including the oldest pterosaur yet found on the continent.

Paleontologists know the bone bed as PFV 393. The late fossil preparator Bill Amaral found the site in 2011 on a field trip to unearth new fossils that might provide information about the origins of organisms we see around us today, such as reptiles and mammals. The fossils were too small to uncover in the field, says Smithsonian National Museum of Natural History paleontologist and study co-author Ben Kligman. So, the paleontology field team enclosed sections of the bone bed in plaster, called “blind jackets,” that would keep the fossils inside safe until they could be uncovered with more delicate methods back at the museum. The fossils within revealed a Triassic ecosystem in detail.

Described by Kligman and colleagues in Proceedings of the National Academy of Sciences, the accumulation of 1,468 fossils includes a range of Triassic organisms both familiar and strange. Scaly fish swam through the prehistoric channels as early frogs kicked through the shallows. Crocodile-like reptiles called phytosaurs watched the shoreline for prey; the dragon-like reptile Vancleavea foraged for small critters; and armadillo-like crocodile relatives called aetosaurs munched on plants and bugs along the banks. And above their heads flew the early pterosaur Eotephradactylus.

From the hundreds upon hundreds of fossils prepared from PFV 393, only three Eotephradactylus fossils have been found so far. The small collection includes a lower jawbone with teeth, an isolated tooth and a finger bone. Nevertheless, the bones show the subtle anatomical hallmarks of pterosaurs. The reptiles originated earlier in the Triassic, splitting off from their common ancestor with dinosaurs, and began to evolve the ability to fly. While feathery, pterosaurs took to the air thanks to hollow bones and leathery wings made of skin stretched between the body and an elongated fourth finger.

Pterosaurs are difficult to find in the fossil record. Their thin, hollow bones were often destroyed before they could be buried and fossilize. “Pterosaurs are cheeky,” says Chinese University of Hong Kong paleontologist Natalia Jagielska, who was not involved in the new study. To become fossils, the flying reptiles would’ve had to be in an environment where there was a chance of being covered before the elements, scavengers or decompositions could destroy the body. “This makes preservation of delicate flying animals in inland environments a rarity,” Jagielska says, and yet somehow Eotephradactylus made it into the fossil record.

The fossils included a clue as to why the pterosaur was found among creatures that lived by streams. While many later pterosaurs had toothless beaks, early pterosaurs like Eotephradactylus were toothy. The teeth from the pterosaur Kligman and colleagues studied were worn down, indicating that the reptile was feeding on relatively hard prey. The small, scaly fish found at PFV 393 seem to be a perfect fit for the tooth wear seen on Eotephradactylus. Scooping up and eating fish kept the pterosaurs coming back to a place where water intermittently flowed, and where sediment could cover bones washed into the channel.

Our analysis of fossil preservation and deposition in this bone bed suggests that abandoned river channels can act as a low-energy setting where delicate bones of animals like pterosaurs might first get deposited. This was not a single unfortunate event, but the result of hundreds of years of animals living in and around a channel.

Ben T. Kligman, first author
Department of Paleobiology
National Museum of Natural History
Smithsonian Institution, Washington, DC, USA.

Bones that tumbled into the channel were then covered over again when monsoons or heavy rains caused the channel to flow with sediment-laden water. The same pattern repeated over hundreds of years.

The pterosaur is not the only remarkable find from the collection of Triassic creatures. While many of the bones are from animals previously found at other sites in Petrified Forest National Park, some are mysterious. A jaw found at the site resembles those of ancient protomammals that were thought to be extinct by the later part of the Triassic. The experts are not sure what the animal was, but it hints at more as-yet-undiscovered species within the park’s rocks.

Taken together, the 16 different vertebrates found at the site indicate how different groups of organisms lived in distinct ecological habitats even during the Triassic. PFV 393 does not contain bones of dinosaurs, predatory crocodiles or other terrestrial creatures found at other sites but instead represents a moist habitat with running water. Even more broadly, the makeup of the organisms at the site demonstrates how different groups of reptiles were moving around the supercontinent Pangea prior to a mass extinction 201 million years ago that ended the Triassic and began the Jurassic.

The pterosaur Eotephradactylus is the oldest pterosaur yet found outside of Europe. The bones indicate how small pterosaurs were expanding to new habitats across Pangaea by 209 million years ago, a broad distribution that almost certainly helped them survive the volcano-driven mass extinction at the end of the period.

Flight is a useful adaptation to have when it comes to survival [because] you can traverse huge distances to meet your dietary needs.

Natalia Jagielska, not involved in the study.
Palaeontologist.
Chinese University of Hong Kong.

Being able to fly and rapidly spread over Pangaea helped pterosaurs diversify into many new forms that gave the group a better chance of long-term survival.

The researchers also highlight turtle fossils found at the site, which can help outline the evolutionary story of the shelled reptiles. Petrified Forest National Park was near the Equator 209 million years ago, and the turtle fossils represent a land-dwelling form with a thin shell and neck spikes. The turtles lived near running channels but were not yet aquatic reptiles at the time.

Kay Behrensmeyer, curator of vertebrate paleontology at the Smithsonian’s National Museum of Natural History, in Petrified Forest National Park documenting the geology of a bone bed in 2023
Ben Kligman

Kay Behrensmeyer (left), curator of vertebrate paleontology at the Smithsonian’s National Museum of Natural History, with Robin Whatley (right), associate dean at Columbia College Chicago, digging for fossils in a Petrified Forest National Park quarry in 2023

Ben Kligman

Previously, a 12-million-year gap loomed between the mass extinction at the end of the Triassic and the closest fossils found in Petrified Forest. Now the gap has been shortened to eight million years, thanks to this new snapshot of life around streams during a time when small, fuzzy dinosaurs ran through forests of towering conifers.

The channels of the time covered and preserved the bones of the creatures that lived in those habitats, everything from fish in the water to flying reptiles above. In fact, Kligman and colleagues propose, such stream deposits in other places might yield essential fossils that further illustrate how the period unfolded through millions of years. Bone by bone, a picture of Triassic life is coming together.

Publication:
B.T. Kligman,R.L. Whatley,J. Ramezani,A.D. Marsh,T.R. Lyson,A.J. Fitch,W.G. Parker, & A.K. Behrensmeyer
Unusual bone bed reveals a vertebrate community with pterosaurs and turtles in equatorial Pangaea before the end-Triassic extinction
Proc. Natl. Acad. Sci. U.S.A. 122 (29) e2505513122, https://doi.org/10.1073/pnas.2505513122 (2025).

Significance
PFV 393 is the first radioisotopically dated (209.187 ± 0.083 Ma old) high-diversity continental vertebrate fossil assemblage to fill a 12-Ma fossil gap preceding the end-Triassic extinction. The taphonomy and depositional setting of this assemblage show that key members of post–Triassic Mesozoic vertebrate communities, including frogs, lepidosaur reptiles, pterosaurs, and turtles, coexisted with archaic lineages such as metoposaurid amphibians, trilophosaurid archosauromorphs, Vancleavea, doswelliids, phytosaurs, and aetosauriforms in the mesic fluvial environments of aridifying equatorial Pangaea approximately 7 Ma prior to the end-Triassic extinction. A member of this paleocommunity and one of the earliest few pterosaurs found outside of Europe, the newly described Eotephradactylus mcintireae gen. et sp. nov., reveals novel aspects of pterosaur mandibular evolution, ecology, and biogeography.

Abstract
Temporally constrained microvertebrate bone beds are powerful tools for understanding continent-scale biotic change. Such sites are rare globally in nonmarine settings during the 12 million years (Ma) preceding the end-Triassic extinction (ETE; ~201.5 Ma), obscuring patterns of faunal change across this interval. A vertebrate assemblage from Arizona, USA, provides unique insights into community composition and ecology prior to the ETE. PFV 393 is a macro- and microvertebrate bone bed preserved in a volcaniclastic fluvial channel-fill with a high-precision U-Pb zircon age of 209.187 ± 0.083 Ma. The fossil assemblage consists of three-dimensionally preserved, delicate, and small skeletal elements of known and new taxa that document a local paleocommunity including hybodontiformes, actinopterygians, actinistians, metoposaurids, salientians, synapsids, lepidosaurs, testudinatans, trilophosaurids, Vancleavea, doswelliids, Revueltosaurus, loricatans, phytosaurs, and pterosaurs. The new early-diverging pterosaur is one of the few Triassic pterosaurs found outside of Europe and the only one with a documented precise radioisotopic age. The testudinatan material shows the rapid dispersal of terrestrial stem-turtles across the Pangaean supercontinent in the Norian and refines temporal constraints on the origin of the turtle shell. The presence of vertebrate lineages endemic to the Triassic highlights their persistence in a mesic, fluvial paleocommunity through a prolonged phase of environmental change preceding the ETE. These lineages coexisted with frogs, lepidosaurs, turtles, and pterosaurs- all key elements of post–Triassic Mesozoic communities. The arrival of turtles and pterosaurs in west-central Pangaea therefore may have been driven by the northward drift of Laurentia from humid equatorial conditions into more arid subtropical latitudes.

B.T. Kligman,R.L. Whatley,J. Ramezani,A.D. Marsh,T.R. Lyson,A.J. Fitch,W.G. Parker, & A.K. Behrensmeyer
Unusual bone bed reveals a vertebrate community with pterosaurs and turtles in equatorial Pangaea before the end-Triassic extinction
Proc. Natl. Acad. Sci. U.S.A. 122 (29) e2505513122, https://doi.org/10.1073/pnas.2505513122 (2025).

© 2025 National Academy of Sciences of The USA.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.

The discovery of a large pterosaur in a 209-million-year-old bone bed within Arizona’s Petrified Forest National Park poses a profound challenge to creationist narratives—particularly those of young Earth creationists who claim the Earth is only 6,000 to 10,000 years old and that all life was created in its present form during a single "Creation Week." This fossil, like many others found in the Triassic layers of the park, is embedded within a well-understood geological context that has been independently dated using radiometric methods to over 200 million years ago. Such precise and consistent dating makes any claim that these creatures lived alongside humans, or were buried during a global flood, entirely untenable.

Moreover, the fossil's location within the Chinle Formation, a stratified sequence of sedimentary rocks laid down over millions of years in fluvial and deltaic environments, further undermines the creationist flood model. The sediments show clear signs of gradual deposition—meandering river channels, ancient soils (paleosols), and seasonal layering—none of which could plausibly be produced by a single, year-long deluge. The fossil record from this site includes not only the large pterosaur but also crocodile-like archosaurs, amphibians, early dinosaurs, and a wide range of plants, all preserved in ecological and evolutionary context. These assemblages are sorted by habitat and time, not by density or "hydrodynamic sorting" as creationists often claim in flood geology.

The real problem for creationists is not just the age of the fossils, but the entire picture they paint. The Triassic fossil beds tell a coherent, evidence-based story of life evolving through time, adapting to changing environments, and sometimes going extinct. This directly contradicts the idea of fixed "kinds" created once and forever. The discovery of the earliest large pterosaur in North America—perfectly adapted for flight and coexisting with other now-extinct forms of life—confirms the deep timescales and evolutionary processes that underpin modern biology and geology. For creationists, accepting this would require abandoning core literalist interpretations of Genesis, making such discoveries not just inconvenient, but fundamentally insurmountable.

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