On Top of the World

We seem to be making an overdue time jump into November: Brian Thomas’ article for Monday is called Tibetan Cat Fossil: A Tall Tale? He opens:

An international research team claims to have found the world’s oldest big cat fossil in Tibet, publishing their findings in the Proceedings of the Royal Society B. Big cats include lions, tigers, jaguars, and even snow leopards from Asia. The team dated several snow leopard-like partial fossils at between 4.1 and 5.95 million years old and a complete skull at around 4.4 million years. But how did the authors obtain these large numbers?

The source for this story is an open access paper published online on the 13th of November, titled “Himalayan fossils of the oldest known pantherine establish ancient origin of big cats.” They say:

Although the oldest pantherine [big cat] fossils occur in Africa, molecular phylogenies point to Asia as their region of origin.

A paradox, in other words – the fossils say that big cats are African and recent, while their genetics say that they are Asian and a bit older. The big news here is a new fossil which is both Asian and older than the other African fossils. They named their new species Panthera blytheae, and say:

A ‘total evidence’ phylogenetic analysis of pantherines indicates that the new cat is closely related to the snow leopard and exhibits intermediate characteristics on the evolutionary line to the largest cats.

My previously mentioned list of interesting web articles suggests that you go hit up Ed Yong for more information on this find and about big cat palaeontology in general, while it also notes the potential for a quote mine of this paragraph from the Nature News article on the paper:

The evolutionarily advanced characteristics of P. blytheae are somewhat surprising, says Lars Werdelin, a vertebrate palaeontologist at the Swedish Museum of Natural History in Stockholm. “I’d have expected something this old to resemble more of a basal [less evolved] cat.”

(Square brackets in original.) In short, if you were just following the African fossil evidence you might have expected that a 4 million year old big cat would look a lot more like the smaller cats the group evolved from. This is not so however – pantherines are older than thought.

There’s much potential here for a creationist to misrepresent the findings here – to say that “big cats have always been big cats” or some such – but Thomas isn’t traversing that road today. Instead, he is again taking aim at the age of the fossils, which in this case are nearly a thousand times older than his universe. He says:

“The fragments were dated using magnetostratigraphy – which relies on historical reversals in the Earth’s magnetic field recorded in layers of rock,” according to BBC News. The method makes use of tiny minerals, in layered sediments for example, that align with Earth’s magnetic field just before hardening into rock, showing that magnetic reversals really happened. But when in history did these reversals occur? Researchers must make assumptions before answering that question.

Fossils found in the same packet of sediment, as magnetically defined, are the same age – this Thomas is prepared to agree. The paper says:

Age. The type locality IVPP ZD1001 is stratigraphically correlated to chron C3n.1r with an estimated age of 4.42 Ma. The stratigraphic range of occurrence of the species based on all available material is from 5.95 Ma (IVPP locality ZD1223, correlated to chron C3r) to 4.10 Ma (IVPP locality ZD1208, correlated to chron C2Ar), or from the end of the Late Miocene to the Early Pliocene.

They have a 4.4 million year old skull (reconstructed in the video at the top of this post) and various other bits and pieces from 5.95 to 4.10 Ma.

In this case, the big cat fossil team cited recent research published in Palaeogeography, Palaeoclimatology, Palaeoecology (P3). The P3 authors aligned certain sedimentary layers from the Tibetan Plateau—including those within which the big cat fossils were found—to age designations noted on a generally accepted version of the geologic chart called the Geomagnetic Polarity Time Scale (GPTS). However, there may be almost as many versions of the GPTS as there are researchers who try to construct them.

The “P³” paper from March cited for the magnetic chrons was actually authored by many of the same people as the big cat fossil paper – they didn’t want to duplicate their work. But the age of a given chron is standardised against the Geomagnetic Polarity Time Scale, and as Thomas notes several different versions have been developed over time. He links to a website which gives four different versions but which claims that Cande and Kent (1995) is most commonly used at present. Thomas bemoans this state of affairs, but neglects to mention that while there are many differences between each scale they tend to agree over the range we’re interested in – compare the first 5 million years of the afore-linked 1995 scale with this one from 1986. He also exagerates the issue slightly when he says that there “may be almost as many versions” as researchers, as each scale seems to have at least two authors.

But the P³ paper isn’t using any of those four scales, instead relying upon a GPTS created by Lourens et al published as part of a reference book called A Geologic Time Scale 2004. Thomas has apparently found this book and reproduces the chart (or at least part of it). I don’t have said book, but have discovered that version 5.4 of a java program called “TimeScale Creator” uses this data (the current version, 6.2, uses the 2012 edition which is potentially different) and so I can effectively zoom in and replicate for you the portion of the scale up to 7 million years that’s important here:

Time Scale

The magnetic chrons are in the central columns. A black area represents a time when the Earth’s magnetic field was in the same direction as it is now, while white is when it was reversed. Chron C3n.1r is the first white patch in the C3 section, C3r is the last white patch in that same section, and C2Ar is the last white patch in the C2A section.

If you checked the previous scales linked you’ll notice that this first 7 million years is again fairly similar to what had been previously determined. So to date their fossils the researchers first had to work out where they were found spectrographically and determine which chron that corresponded to. They then checked with their reference book to see what age this means the fossil was from, and it turns out that it doesn’t really matter which reference they used as they are all fairly similar – at least, they aren’t going to produce anything like the thousandfold overestimation that the YEC timescale demands exists.

But how do we know how old the chrons are? Thomas takes a pot shot at the biostratigraphic information in the right-hand columns, and then says:

Yet, do biostratigraphy and magnetostratigraphy supply independent lines of evidence that demonstrate ages of millions of years? Not at all—because both methods assume millions of years in the first place.

When available, secular researchers use radioisotope dating to pin certain magnetic or fossil layers to the geologic time scale, so both methods rely on the same isotope “ages.” One problem with this approach is that the most often used argon-based isotope methods yield excessively old ages for samples known to be much younger.

To get absolute ages from the relative ages of the magnetic chrons and plankton you need radioisotopic dating, which Brian Thomas doesn’t like. He doesn’t actually go into a serious discussion of where the problems are, merely pointing the reader to the argon dating experiments we discussed on Wednesday. “Sometimes they use argon,” he’s effectively saying here, “and if you don’t know what you’re doing you can get inaccurate results using that method.” Not a great argument.

He concludes:

In short, these supposedly separate dating methods both rest upon a third, disproven method! Was the Tibetan big cat fossil stash really millions of years old? Those who use these dating techniques ignore that the technology used to arrive at these dates has been falsified, and they ignore historical accounts of creation and the Flood.

Perhaps the best information available about the past is a soberly written account of the world’s earliest events, which is not subject to constant revision—the book of Genesis.

There are many things I could say about this, but let’s look at what the young Earth creationist “biblical” explanation must look like. As Thomas said, he’s prepared to accept that the magnetic field of the Earth has flipped over time, but creationists generally tie this to the Flood. This fossil is clearly post-Flood, but over the known lifetime of the species the Earth’s field has flipped 8 times, and since then another 15. The modification of the Earth’s magnetic field in this way is a Big Event, another one of which may end up being the result of the magnetic changes that we have been observing over the last couple of hundred years, and it requires significant changes in the movement of currents of magma in the Earth’s mantle. Young Earth creationists need to compress more than 23 such pole flips over less than 4000 years (more than 1 every 200 years). They also need to explain how all this is physically possible.

That last part could be quite the ask, but Brian Thomas isn’t the man for the job.

3 thoughts on “On Top of the World

  1. YECs Aren’t intrested in providing explanations. They have all they need in that “soberly written account. All they are trying to do is demonstrate to the wavering that science is at least neutral and at best chimes with their stories.
    Creation science isn’t science; it’s religious apologetic.

  2. How typical of Thomas to quibble about the exact age, when if the authors are right by within even orders of magnitude his model is sunk, which of course it is by mountains of other evidence as well. Of course he does not mention that if his model were correct we should find cats and other large modern mammals throughout the fossil record, including the Paleozoic and early Mesozoic, where not one hint of them occurs, while ZILLIONS of fossils of expected creatures do occur. This flies directly in the face of YECIsm, yet YECs either or offer supposed explanations (eco zonation, differential escape, and hydro sorting), which fail miserably to explain the overall patterns, and often only make matters worse (for example, any hydro sorting would tend to sort large modern mammals with similar sized dinosaurs).


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