Can Pristine Fossils Be Old?
Cases of exceptional preservation in fossils
should raise questions about alleged deep time
After an animal dies, does it become a fossil? Not usually. Its remains are quickly consumed by other organisms, including worms and bacteria. Marine organisms are often consumed on the way down, and if they reach the ocean floor, there are plentiful microbes to make use of the organic remains. Otherwise, wouldn’t whale carcasses pile up on the ocean floor after millions of years? After so much time, why don’t we see stacks of whales, fish, turtles and sharks hundreds of feet deep at the bottom of the sea? Even shipwrecks have a finite existence. The Titanic is being consumed in our own lifetimes by rust-eating bacteria.
Unless an organism is buried quickly, it will not become a fossil. Even then, there are underground organisms that continue the recycling process. Worms and other burrowing animals perform “bioturbation,” plowing up and scattering the layers, allowing microbes to consume the original biological matter. Unless the organic material becomes permineralized (replaced by minerals), it should disappear in a short time. On top of that, geological processes such as water seepage, earthquakes, volcanic eruptions and plate tectonics eventually take their toll. The more time, the more damage. Why would anything remain after tens or hundreds of millions of years?
Think of these destructive factors as we look at recent cases of exceptional preservation in the fossil record.
Snails: 2+ Million Years
Study reveals early diagenetic processes of fossil land snail shells from the Chinese Loess Plateau (Phys.org, 10 Feb 2023). The Chinese Loess Plateau (loess meaning loose sediments of wind-blown dust) was formed in the last 2.6 million years, geologists say. In the loose deposits, there are snails. Lots of them. Wouldn’t the fragile shells become crushed and altered by dynamic chemical and physical process (diagenesis) while they sat there, becoming slowly covered up by wind-blown (eolian) dust and sand?
Terrestrial mollusks [snails] are considered as typical “index animals” due to their sensitivity to climate change. They are widely distributed in the semi-arid to arid region of China, including the Chinese Loess Plateau (CLP).
Despite the wide application of geochemical proxies of fossil snail shells in paleoclimatic reconstruction, the extent that they were influenced by the diagenetic alteration remains unknown.
The Chinese team used Raman spectroscopy and found no alteration in the minerals of the fossil shells compared to modern shells. In addition, they found traces of carbon-14, which should have been completely decayed in just 100,000 years. They found elevated traces of uranium oxides, which allowed them to claim confident dates for the shells. But given the potential amount of diagenetic alteration, including absorption of uranium by water, do the scientists really know how to untangle all the processes and interpret their results? Modern snail shells of the same species do not appear essentially different from the fossil shells.
However, the apparent closed system U-Th ages of fossil Cathaica sp. shells are found to be systematically younger (~6,000 to 13,000 years) than their paired shell 14C ages. By evaluating possible U uptake scenarios, the researchers suggest that this apparent age discrepancy is related to the early diagenetic uptake of U and later close system behavior likely due to the isolation of fossil shells from the influence of pore waters.
The original paper is open access: Tao Li et al., Early diagenetic imprints and U–Th isotope systematics of fossil land snail shells from the Chinese Loess Plateau, Quaternary Geochronology, Volume 74, February 2023, 101417.
Fossil Feathers: 100+ Million Years
Rare fossilized feathers reveal secrets of paleontology hotspot during Cretaceous period (Frontiers in Earth Science via Phys.org, 10 Jan 2023). Also from China but much older in the geological time scheme, a fossil bird shows remarkable preservation of fine details said to be over 100 million years old. Five specimens of the extinct bird Sapeornis were found in the Jehol fossil bed and examined:
The site of Jehol Biota in China is famous for stunning fossils which preserve soft tissue—skin, organs, feathers, and fur. These fossils offer rare insights into the evolution of characteristics like flight, but they need careful interpretation to understand what the soft tissue looked and behaved like in life, and how decomposition may have affected it.
The original paper is open access here: Yan Zhou et al., Taphonomic analysis of the exceptional preservation of early bird feathers during the early Cretaceous period in Northeast China, Frontiers in Earth Science, 17 Jan 2023. Two of the conclusions are quoted here:
3) The redox-sensitive trace elements of host sediments indicate that the bottom waters of the paleolake where Sapeornis STM 15-36 was buried are anoxic, restricted, and sulfidic. This deposition environment protected Sapeornis STM 15-36 from bioturbation and hydrodynamic disturbance to a large extent, allowing its whole set of feathers to be delicately preserved.
4) We preliminarily propose that a strong and short rain flow brought Sapeornis STM 15-36 to lake interior rapidly and then buried it quickly by the accompanying terrestrial debris. With the subsequent anoxic burial environment, a complete set of feathers of Sapeornis STM 15-36 was delicately preserved.
This paper merits careful scrutiny by Darwin skeptics to determine whether the interpretation is plausible, or whether special pleading was employed to keep the fossils millions of years old.
Fish Brains: 300+ Million Years
319-million-year-old fish preserves the earliest fossilized brain of a backboned animal (University of Michigan, 1 Feb 2023). How much could change in 319 million years? The UMich team that studied a fish fossil with a CT scan found details of the fish’s brain inside the rock.
The brain and its cranial nerves are roughly an inch long and belong to an extinct bluegill-size fish. The discovery opens a window into the neural anatomy and early evolution of the major group of fishes alive today, the ray-finned fishes, according to the authors of a University of Michigan-led study scheduled for publication Feb. 1 in Nature.
They are not claiming that original soft tissue was preserved, but finding details this precise should raise questions. Obviously some time elapsed between the day the fish was buried and when it became fossilized. Did no burrowing animals, microbes or earthquakes disturb the brain impression for 319 million Darwin years? Watch the two-minute video in the article and ponder the amount of soft tissue detail in this fossil.
The paper in Nature is behind a paywall: Figueroa et al., Exceptional fossil preservation and evolution of the ray-finned fish brain. Nature, 1 Feb 2023.
Here we report brain and cranial nerve soft-tissue preservation in Coccocephalus wildi, an approximately 319-million-year-old ray-finned fish. This example of a well-preserved vertebrate brain provides a window into neural anatomy deep within ray-finned fish phylogeny. Coccocephalus indicates a more complicated pattern of brain evolution than suggested by living species alone, highlighting cladistian apomorphies and providing temporal constraints on the origin of traits uniting all extant ray-finned fishes. Our findings, along with a growing set of studies in other animal groups, point to the importance of ancient soft tissue preservation in understanding the deep evolutionary assembly of major anatomical systems outside of the narrow subset of skeletal tissues.
If one takes away the assumptions of deep time and evolution, this fish does not look all that different from modern bluefins. They can’t see it shows a clear evolutionary sequence, so they say, ‘it’s complicated.’ In their thinking, traits “emerge.” Anatomical systems “assemble.” Stuff happens.
Deep time is not the answer. It’s the problem.