Rosa Rubicondior: Creationism Refuted - Highly Accurate Dating of Dinosaur Eggs

Sunday, 21 December 2025

Creationism Refuted - Highly Accurate Dating of Dinosaur Eggs

The Gobi Desert, where many dinosaur eggs have been found.

Dinosaur eggshells unlock a new way to tell time in the fossil record | Stellenbosch University

This paper will have creationists searching for reasons to dismiss evidence that would, if they were prepared to accept it honestly, force them to concede that their beliefs are wrong. It reports a discovery by researchers at Stellenbosch University showing that dinosaur eggshells can be dated with a high degree of precision using an already well-established technique: uranium–lead (U–Pb) radiometric dating.

Until now, U–Pb dating has been most famously applied to zircon crystals in volcanic ash, where the age can be determined by measuring the ratio of radioactive uranium isotopes to the stable lead isotopes produced by their decay. In this study, however, the same underlying principles are applied to calcite crystals preserved in dinosaur eggshells.

The scientists have published their method, open access, in the journal Communications Earth & Environment.

Why uranium–lead (U–Pb) dating is reliable — and common objections fail. Uranium–lead (U–Pb) dating is one of the most thoroughly tested and internally self-checking methods of radiometric dating. It is based on well-understood nuclear physics and is used precisely because it is resistant to the kinds of problems often raised by critics.

dating uses *two separate radioactive decay chains* at the same time:

Uranium-238 decays to Lead-206
Uranium-235 decays to Lead-207

These isotopes decay at different, precisely measured rates. If both decay chains yield the same age, the result is not an assumption but a powerful internal verification. If they disagree, the data immediately reveal that something has gone wrong.

No assumption of “starting lead” A common claim is that radiometric dating assumes no lead was present at the start. In reality, U–Pb dating explicitly tests for this. Any non-radiogenic (“common”) lead can be measured and mathematically accounted for. The method does not require zero initial lead, and disagreement between the two decay systems would expose any incorrect assumption.

Closed systems are tested, not assumed
Critics often argue that minerals are not closed systems. U–Pb dating directly checks this. If uranium or lead has been added or lost, the two decay chains will diverge in predictable ways. Such samples are rejected or corrected using concordia–discordia analysis. The method includes its own built-in falsification test.

Decay rates are not guesses
Radioactive decay rates are governed by nuclear forces and are unaffected by temperature, pressure, chemical environment, or geological processes. These rates are measured repeatedly in laboratories and confirmed by natural nuclear reactors (such as Oklo) and astronomical observations. No evidence exists that decay rates have changed in Earth’s history.

Precision comes from physics, not interpretation
U–Pb ages are calculated directly from measured isotope ratios using known decay constants. The process is quantitative, reproducible, and independent of fossil interpretation, sedimentation rates, or evolutionary assumptions.

Why eggshells can be dated
Calcite crystals in dinosaur eggshells can incorporate uranium shortly after burial while excluding lead. As radioactive decay proceeds, lead accumulates within the crystal lattice. Measuring these isotopic ratios allows the time since fossilisation to be determined directly — not inferred from surrounding rocks.

In short:
U–Pb dating does not rely on circular reasoning, unverifiable assumptions, or evolutionary bias. It uses redundant decay systems, tests its own assumptions, and produces results that either agree internally or fail transparently. That is why it is trusted — and why dismissing it requires ignoring how the method actually works.

The research is also explained in a video accompanying a Stellenbosch University news release.

Dinosaur eggshells unlock a new way to tell time in the fossil record

Novel method developed to date fossilized dinosaur eggshells.
Regarded as a breakthrough to date the age of fossil-bearing rocks.

An international team of geologists and paleontologists is pioneering a groundbreaking methodology to reliably determine the age of fossil-bearing rocks — by directly dating fossilized dinosaur eggshells.

The study, led by Dr Ryan Tucker from Stellenbosch University’s Department of Earth Sciences, was published in Communications Earth & Environment.

Many fossil sites around the world are only coarsely dated. Without precise information on the geologic age of fossils, paleontologists struggle to understand how different species and ecosystems relate across time and space. Usually, researchers rely on dating minerals such as zircon or apatite found associated with fossils, but those minerals aren’t always present. Attempts to date the fossils themselves, such as bones or teeth, have often produced uncertain results.

Dr Tucker's team, consisting of MSc student Kira Venter and Prof Cristiano Lana from the Elemental and Isotope Analysis Laboratory at SU's Central Analytical Facilities, took a different approach. They used advanced uranium–lead (U–Pb) dating and elemental mapping to measure trace amounts of uranium and lead housed inside the calcite of fossilized dinosaur eggshells. These isotopes function like a natural clock, enabling scientists to determine when the eggs were buried.

View video on novel method.

Tests on dinosaur eggs from Utah (USA) and the Gobi Desert (Mongolia) showed that the eggshells record ages with an accuracy of about five percent relative to precise volcanic-ash dates. In Mongolia, the team determined the first-ever direct age — around 75 million years old — for a historic locality preserving dinosaur eggs and nests.

Eggshell calcite is remarkably versatile. It gives us a new way to date fossil sites where volcanic layers are missing, a challenge that has limited paleontology for decades.

Dr Ryan T. Tucker, lead author.
Department of Earth Sciences
Stellenbosch University
Stellenbosch, South Africa.

The work involved collaborators from the North Carolina Museum of Natural Sciences, North Carolina State University, Colorado School of Mines, Mongolian Academy of Sciences’ Institute of Paleontology, Universidade Federal de Ouro Preto (Brazil). Fieldwork in Mongolia was carried out through the Mongolian Alliance for Dinosaur Exploration (MADEx) and supported by the National Geographic Society and the National Science Foundation.

By showing that dinosaur eggshells can reliably record the passage of geologic time, the study links biology and Earth science in a new way — offering researchers a powerful tool to date fossil sites around the globe.

Direct dating of fossils is a paleontologist’s dream. Armed with this new technique, we can unravel mysteries about dinosaur evolution that used to be insurmountable.

Associate Professor Lindsay E. Zanno, co-author
Department of Earth Sciences
Stellenbosch University
Stellenbosch, South Africa.

Publication:
Tucker, R.T., Venter, K.E., Lana, C. et al.
U-Pb calcite age dating of fossil eggshell as an accurate deep time geochronometer.
Commun Earth Environ 6(872) (2025). https://doi.org/10.1038/s43247-025-02895-w

For creationists, this development closes yet another escape route. One of the most persistent tactics has been to claim that fossils cannot be dated directly and that ages are merely inferred from surrounding rock layers. Uranium–lead dating of dinosaur eggshells removes that line of argument entirely. The age comes from the fossil material itself, using a method grounded in nuclear physics rather than geological interpretation.

It also undercuts the familiar assertion that radiometric dating depends on special assumptions that conveniently favour evolutionary timescales. The U–Pb method uses two independent decay systems that act as mutual checks on each other. Any disturbance, contamination, or incorrect assumption would be immediately apparent in the data. The reliability of the result is not asserted; it is demonstrated.

Most damaging of all, this technique produces ages that are entirely incompatible with a young Earth. There is no plausible way to compress hundreds of millions of years of radioactive decay into a few thousand without invoking unknown physics, selective miracles, or wholesale rejection of the very nuclear processes that modern technology relies upon. At that point, the objection is no longer scientific but theological.

As with so much in the fossil record, the problem for creationism is not a lack of evidence but an excess of it. Each new method that allows the past to be read more clearly tightens the constraints on reality. Dinosaur eggshells, it turns out, carry not just embryos but timestamps — and they record a history far older than creationism can tolerate.

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