Wednesday, 11 May 2022

Evolution News - Why North American Fossils from 95 Million Years Ago Look Like Tropical Fossils

Cretaceous oysters of the genus Pycnodonte investigated in the new study. These specimens were collected in San Miguel County, Colorado (top left), Kane County, Utah (top right), Big Horn County, Wyoming (bottom left), and Natrona County, Wyoming (bottom right), with a penny for scale.
Image credit: Matt Jones
Bali-like temperatures in Wyoming? Fossils reveal tropically hot North America 95 million years ago | University of Michigan News

Gullible fools who have been conned into believing, despite all the evidence showing otherwise, that planet Earth is just a few thousand years old, for no better reason than their mummy and daddy had been fooled into believing it, will need to ignore this evidence as well.

It is evidence that not only were fossils of highly evolved species being laid down in Wyoming, USA, 95 million years ago, but that the climate there at that time was more like that in tropical regions of Earth today.

The new study, by researchers from the University of Michigan shows that much of western North America, 95 million years ago, was covered by a shallow sea as warm as today’s tropics. The existence of this sea coincided with the "Cretaceous Thermal Maximum", one of Earth's hottest periods in the past 100 million years.

According to information supplied by the University of Michigan:

These data indicate that the North American interior during the peak of the Cretaceous greenhouse was as warm as the hottest conditions in the modern-day tropics—imagine the climate of Bali, Indonesia, in places like Utah or Wyoming.

Many generations of geologists have studied the paleontology and stratigraphy of the Western Interior Seaway, providing different ideas about past climate and a foundation of knowledge that made this study possible, however, no direct paleothermometer measurements existed—until now—from the interior of North America for the peak of this Cretaceous greenhouse world.

This paucity of records has hindered solid understanding of the temperature evolution of North America through the Cretaceous and the influence of temperature on the continent’s marine biotas in the seaway, as well as on terrestrial fauna like the dinosaurs inhabiting the adjacent coastal plains.

Dr Matt Jones, lead author
Formerly of University of Michigan
Now with the Smithsonian Institution’s National Museum of Natural History.
The study found that average water temperatures in the Western Interior Seaway during the mid-Cretaceous ranged from 28 to 34 degrees Celsius (82 F to 93 F), as warm as modern tropical extremes like the Indo-Pacific Warm Pool, which consistently exhibits the highest water temperatures over the largest expanse on the Earth’s surface.

Atmospheric carbon dioxide concentrations in the mid-Cretaceous are still a topic of debate among researchers, but many studies have shown levels in excess of 1,000 parts per million. Today’s levels are a bit over 420 ppm but could surpass 1,000 by the end of this century unless fossil-fuel emissions are curtailed, according to climate scientists.

To determine just how hot North America was during the peak Cretaceous greenhouse world 95 million years ago, the researchers analyzed 29 well-preserved oyster shells from a U.S. Geological Survey fossil collection.

Cross-sectional view of the cut and polished surface of a Cretaceous oyster (Exogyra trigeri) from the Mancos Shale Formation in McKinley County, New Mexico, with a penny for scale.

Image credit: Jon Hoffman
The fossils came from sandstone and shale outcrops in Wyoming, Colorado, Utah, New Mexico and Arizona—locations that were at a similar latitude as today but were underwater during the Cretaceous. At that time, the Western Interior Seaway stretched from the Gulf of Mexico to the Arctic and from present-day Utah to Iowa.

These new findings help resolve temperatures in North America during a peak greenhouse warmth interval in the geologic past, which in turn may help us better predict just how warm Earth may be in the future under projected higher atmospheric CO2 conditions.

Even after working with the clumped isotope paleothermometer for 15 years, it’s still amazing to me that, given the right samples, we can essentially dip a thermometer into a 95-million-year-old ocean and figure out how warm it was. If we want to be able to better predict how different life on Earth may respond to future warming, concrete temperature estimates in past warm periods can help us set upper limits on survivability.

Assistant Professor Sierra Petersen
Department of Earth and Environmental Sciences.
University of Michigan, USA
Fossils collected across the western interior of the U.S. show that the seaway teemed with marine life including massive clams, spiral-shelled ammonites and extinct types of oysters. Dinosaurs roamed the adjacent coastal plains.

Map shows the shoreline of North America’s Western Interior Seaway 94 million years ago. Dots indicate sites where fossil oyster shell specimens were collected. Samples from those shells were analyzed at the University of Michigan using a technique called clumped isotope paleothermometry.

Illustration credit: Matt Jones
For the current study, researchers used fossil oyster shells collected over several decades by Bill Cobban, one of the preeminent American paleontologists of the 20th century, and his colleagues. As the oysters grew, their shells incorporated various forms, or isotopes, of the elements oxygen and carbon, in ratios that reveal the temperature of the surrounding seawater.

With a small Dremel drill, Jones sampled the fossil shells and collected the powdered calcite. Using a state-of-the-art mass spectrometer in Petersen’s U-M lab, the researchers measured the isotopic ratios of carbon and oxygen. Specifically, they looked at the occurrence of the heavy carbon isotope carbon-13 and the heavy oxygen isotope oxygen-18, and how often they were found bound together in the calcite crystal structure.

North American data from the new study is consistent with previous studies that used traditional oxygen isotope paleothermometry techniques at open-ocean sites globally, according to the authors. Those earlier studies, which measured the ratio of stable isotopes of oxygen, inferred sea-surface temperatures in the high 20s C (low 80s F) from the sub-Antarctic to the mid-30s C (upper 90s F) from the tropics and southern mid-latitudes.

In addition to the specific findings quantifying past global warmth in the Western Interior Seaway, the new study also demonstrates how this particular geochemical technique can be used to reveal climate conditions in the deep past, where prior techniques have struggled.
The authors give more technical detail in the abstract to their published findings in Geology:
The mid-Cretaceous thermal maximum (KTM) during Cenomanian to Santonian times from ca. 100 to 83 Ma is considered among Earth’s warmest sustained intervals of the Phanerozoic. The time interval is also characterized by major paleoceanographic changes in the form of an oceanic anoxic event and the flooding of epicontinental seaways, such as the Western Interior Seaway in North America. We report carbonate clumped isotope (Δ47) paleotemperatures (TΔ47) of the KTM measured from Cenomanian oyster fossils of the Western Interior Seaway. Following screening of specimens for carbonate diagenesis and exclusion of geographic zones with evidence consistent with solid-state Δ47 reordering, a mean TΔ47 of 28–34 °C (95% confidence interval for the standard error of mean) for primary oyster calcite quantifies extreme mid-latitude warmth in North America. When combined with existing Campanian and Maastrichtian marine TΔ47 records, the new data constrain Late Cretaceous temperature trends underlying the evolution of North American faunal and stratigraphic records. These TΔ47 data from the peak KTM highlight the potential of this proxy to quantitatively resolve the upper thermal limits of Phanerozoic greenhouse climates.
It takes such extraordinarily agile mental gymnastics to maintain the infantile superstition that Earth is just a few thousand years old, despite evidence such as this, that it can only really be explained as a mental disorder such as acute, theophobic psychosis - an acute anxiety disorder that renders the sufferer too terrified to emerge out of the rabbit hole he/she was stuffed into as a child and look dispassionately at the real-world. The mental paralysis that it frequently causes is another good reason to reject religion.

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