Showing posts with label Palaeobiology. Show all posts
Showing posts with label Palaeobiology. Show all posts

Friday, 8 November 2024

Refuting Creationism - How Eggs Evolved Hundred of Millions of Years Before Chickens


Chromosphaera perkinsii resembles the early stages of animal embryo development during its multicellular life stage
DudinLab
The egg or the chicken? An ancient unicellular says egg! - Medias - UNIGE

Scientists believe they may have cracked the chicken and egg 'problem' that creationists have been fooled into thinking is a killer problem for the Theory of Evolution. With their child-like understanding of evolution, creationists can't imagine how species emerge over time from earlier species by a process of evolution and think that their mythical magic creation without ancestors is actually what happens, or at least what evolutionary biologists think happens. So, they imagine explaining how the first chicken hatched from the first egg before there was a chicken to lay it, is an insurmountable problem.

In fact, of course there never was a first chicken just as there never was a first human, and eggs are simply a phase in the life cycle of, in this case, chickens, so hens' eggs are chickens just as much so as adult hens are. The ancestral species that the Southeast Asian jungle fowl evolved from had been laying eggs ever since they diverged from the egg-laying avian dinosaurs that had evolved from the egg-laying theropod dinosaurs, etc, etc, back to the egg-laying tunicates and chordates in the Cambrian and their egg-laying ancestors...

Wednesday, 30 October 2024

Refuting Creationism - Walking With Dinosaurs 70-75 Million Years Before 'Creation Week'


Paleontologists discover Colorado ‘swamp dweller’ that lived alongside dinosaurs | CU Boulder Today | University of Colorado Boulder

Paleontologists dig for fossils in northwestern Colorado.
Credit: John and ReBecca Foster.
AI-Generated illustration of life in a Cretaceous swamp near the Western Inland Seaway

ChatGPT4o
For some reason creationists have a fixation with dinosaurs, probably because, deep down, they know their existence refutes the biblical nonsense of an Earth that's only 6-10,000 years old. After all, there is nothing quite like a 75 million-year-old fossil of a living creature for falsifying the idea that the Universe, Earth and life on it were all created in a single week, just a few thousand years ago.

So, their cult leaders are forever scraping around trying to find evidence that human beings and dinosaurs lived together and even that Jesus would have been familiar with T. rex or Diplodocus and was probably used to pterosaurs flying overhead. But of course, there is none - which was never a reason for a creationist to abandon a delusion.

What there is, however, is evidence that dinosaurs were around until about 66 million years ago then promptly went extinct to be replaced by birds and mammals as the dominant terrestrial life forms.

And now we have evidence of an early mammal living amongst dinosaurs in what if now Colorado, USA. Sadly, there is no evidence that the early mammal resembled Jesus or any other humans for that matter; it was more like a muskrat.

Wednesday, 18 September 2024

Refuting Creationism - Aotearoa New Zealand's Rich Fauna - 20 Million Years Before 'Creation Week'


Artist's impression of the Miocene landscape of Aotearoa New Zealand’s South Island
Kākāpō are the true ancient species of Aotearoa… | Canterbury Museum

The Bronze Age Middle Eastern Pastoralists who made up the Hebrew origin myths could have known nothing about a southern hemisphere, let alone archipelagoes like New Zealand (or to give the name that more accurately reflects its dual cultures, Māori and European, Aotearoa New Zealand) and they knew nothing of the rich history of Earth's wildlife, so they said not a word about it in their mythology.

So, we have the ludicrous situation where a sizable proportion of people - especially Americans - think nothing older than about 10,000 years and nothing that wasn't known to parochial Middle Eastern pastoralists, ever existed, despite the abundant evidence that it did and that it had ancestors very much older.

What information do you have on the St* Bathan's fauna found in the Bannockburn Formation on New Zealand's South Island? The St. Bathans Fauna is a remarkable fossil assemblage from the Early Miocene (around 19-16 million years ago) found in the Bannockburn Formation in New Zealand's South Island. Discovered near the small town of St. Bathans, this fossil site is part of the Manuherikia Group, which is known for providing a window into New Zealand's unique prehistoric ecosystem.

Here’s a detailed overview of the St. Bathans fauna and its significance:
  1. Paleontological Importance
    • The fossils represent a critical period when New Zealand was transitioning from being an isolated landmass with its own flora and fauna. This period is significant for the evolution of New Zealand's unique species after it split from Gondwana.
    • The St. Bathans Fauna provides insights into how climate change affected New Zealand's environment and species during the Miocene epoch. At that time, the region was much warmer and covered with subtropical forests and wetlands, a stark contrast to the cooler, drier conditions that followed in the Pliocene and Pleistocene.
  2. Vertebrate Fossils
    • Birds: The site is most famous for its extensive and diverse avian fossil record. Notable examples include:
      • The giant flightless bird species similar to moa (though these are not the moa we are familiar with).
      • Ancient species of waterfowl, shorebirds, and parrots, some of which are now extinct.
      • Fossils of a possible heron species, various songbirds, and even a previously unknown eagle.
    • Mammals: Mammal fossils in New Zealand are rare, but the St. Bathans site yielded intriguing examples of early mammals. These include:
      • A small, shrew-like mammal (perhaps representing one of the only land mammals known in New Zealand before humans introduced others).
      • Marsupial fossils that hint at a lineage distinct from modern marsupials in Australasia.
    • Reptiles: Various lizard and possible gecko remains have been found, along with fossils that may represent tuatara ancestors.
    • Fish: Several species of freshwater fish, especially primitive forms such as galaxiids, have been found, showing that New Zealand's fish diversity extended back tens of millions of years.
  3. Flora
    • Plant fossils from the same region indicate that the Miocene landscape was densely vegetated with subtropical and temperate plants, including ferns, conifers, and flowering plants. The existence of forests and wetlands provided ideal habitats for the wide variety of animals found there.
  4. Significance for Climate and Ecological Studies
    • The St. Bathans fauna gives researchers a clear picture of what New Zealand's environment was like during a warmer period of Earth's history, making it invaluable for studies on climate change and its impact on ecosystems over time.
    • It shows a diversity of life forms that existed before the drastic cooling in the Pliocene, which led to the extinction of several species.
  5. Unique Species
    • One of the notable discoveries includes a species dubbed the "St. Bathans mammal," which is a mysterious, small mammal species. New Zealand is generally known for its lack of native land mammals, but this discovery suggests that mammals may have once been present in ancient New Zealand, challenging previous assumptions.
    • Bird species found in the Bannockburn Formation are also unique, some showing traits that link them to extinct lineages or suggest evolutionary connections with species outside New Zealand.

The St. Bathans fossil site continues to be a rich source of paleontological discovery, providing ongoing insights into the Miocene ecosystems of New Zealand and the biogeographical history of its fauna and flora.
For example, palaeontologists are discovering more fossils of the so-called St Bathan's fauna that charcterised Aotearoa New Zealand's South Island, most of which are of extinct species. These are being found in rocks known as the Bannockburn Formation that formed in an ancient lake by a team led by Associate Professor Trevor Worthy of Flinders University, Australia and including Dr Paul Scofield, senior curator of natural history, Canterbury Museum, Christchurch, Aotearoa New Zealand. They have recently published their findings, open access, in the journal Geobios:
Kākāpō are the true ancient species of Aotearoa New Zealand
Aotearoa New Zealand’s true ancient species are animals like Kākāpō, small wrens, bats and freshwater limpets, not recent Aussie immigrants like kiwi, moa and takahē.
This is the conclusion reached by an international team of palaeontologists after two decades of groundbreaking research at the St Bathans fossil site in Central Otago recently published in Geobios.

The team, including Canterbury Museum Senior Curator Natural History Dr Paul Scofield, have been excavating the large St Bathans site since 2001, uncovering thousands of fossil bones. The site, which was once at the bottom of a large prehistoric lake, offers the only significant insight into Aotearoa‘s non-marine wildlife from 20 million years ago.

The new research summarises the extraordinary creatures discovered in the more than 9,000 specimens collected across 23 years. Exotic creatures identified at the site include a giant parrot that the scientists nicknamed “Squawkzilla”, two mystery mammals, flamingos, a 3-metre crocodile, a giant horned turtle and a giant bat.

Reconstruction of the 1m tall giant parrot Heracles inexpectatus, dwarfing a bevy of 8 cm high Kuiornis – small New Zealand wrens scuttling about on the forest floor.

Illustration: Dr Brian Choo, Flinders University.
Paul Scofield, who has been involved in digs at St Bathans since 2002, said the research had prompted a rethink of our native fauna.

Many of the species that we thought of as iconic New Zealand natives – a classic example would be the takahē – we now know are relatively recent blow-ins from Australia, arriving only a few million years ago. Twenty-three years of digging at St Bathans has changed our idea about the age of the New Zealand fauna and the importance of some animals over others. For example, until now we thought that birds like kiwi and moa were among the oldest representatives of New Zealand fauna. We are now realising that the Kākāpō, tiny New Zealand wrens and bats, and even a bizarre freshwater limpet, are the real ancient New Zealand natives.

Dr Paul Scofield, co-author
Canterbury Museum
Christchurch, New Zealand


The research concludes that this menagerie of exotic animals was wiped out by dramatic temperature drops over the last about 5 million years.

Lead author Flinders University Associate Professor Trevor Worthy said 23 years of research at St Bathans had transformed our understanding of how non-marine vertebrate life in New Zealand looked around 20 million years ago during the Early Miocene era.

It’s exciting to be involved in a project that continues to make absolutely fresh discoveries about what animals lived in New Zealand’s lakes and rivers, and the forests around them, during this critical period in history. Every year we find new specimens. Finds that reveal amazing new species that we couldn’t have imagined when we first started working there.

Associate Professor Trevor H. Worthy, lead author
College of Science and Engineering
Flinders University
Adelaide, South Australia, Australia

Study co-author Dr Vanesa De Pietri of the University of Canterbury said the animals that lived in New Zealand 20 million years ago were very different to what we have now.

For example, we had another giant eagle that was not related to Haast’s Eagle. We had a whole bunch of songbirds that were quite different, crocodiles and even potentially a small mammal that we’ve nicknamed the waddling mouse. We are still in the middle of our research into understanding exactly what that was.

Dr Vanesa L. De Pietri, co-author
School of Earth and Environment
University of Canterbury
Christchurch, New Zealand.

The latest research paper was a collaboration between Flinders University, Canterbury Museum, Te Whare Wānanga o Waitaha University of Canterbury, The University of Queensland, University of Copenhagen and University of New South Wales.
Artist's impression of the St. Bathans Fauna. Source: New Zealand Geographic
Illustrations: Tom Simpson
Abstract
The St Bathans Fauna, from sites near the village of St Bathans, Central Otago, South Island, is the first substantive pre-Quaternary terrestrial vertebrate fossil fauna discovered in New Zealand. This fauna derives from 33 sites or discrete sedimentary beds located in the lower 50 m of the lacustrine Bannockburn Formation, Manuherikia Group, and is generally accepted as local stage Altonian (19–15.9 Ma; Burdigalian, Early Miocene) in age. Investigations since 2001 have revealed an abundant and diverse fauna from over 9000 catalogued lots that is herein reviewed. Invertebrates notably include eight genera and species of terrestrial molluscs. Among vertebrates, freshwater fish remains dominate with 17 species evidenced by 16,500 analysed otoliths (genera Neochanna, Galaxias, Prototroctes, and Mataichthys) and many thousands of bones. Birds (minimally 45 species, several thousand bones) are the most common non-fish vertebrates, among which waterfowls dominate all assemblages (10 species). Co-occurring with these was a diverse herpetofauna, including undetermined crocodylians and a terrestrial turtle, both absent in Recent faunas. Significantly, the St Bathans Fauna evidences that Zealandia already had all of New Zealand’s ‘old’ endemic Recent taxa (sphenodontids, leiopelmatids, dinornithiforms, apterygids, aptornithids, strigopoid parrots, acanthisittids, and mystacinids) during the Early Miocene. Furthermore, it includes Australasia’s oldest ardeids, two flightless rallids, a novel higher landbird family, a greater diversity of bats, and terrestrial mammals. All sites reflect a single fauna, except that the ducks Manuherikia lacustrina (stratigraphically lower in section) and M. primadividua (higher) have a mutually exclusive distribution that is not yet correlated with any other biotic distribution differences.

1. Introduction New Zealand is a small emergent part of the India-sized continent of Zealandia that is largely submerged and from which New Caledonia, Lord Howe, Norfolk Island, the Chatham Islands, and the New Zealand subantarctic islands all project (Mortimer et al., 2017, Strogen et al., 2023). The New Zealand archipelago includes 800+ islands >1 ha, totalling 270,000 km2, of which North Island (114,740 km2) and South Island (151,120 km2) are the largest. Mainland New Zealand (North and South islands) averages ca. 2000 km from Australia. Seafloor-spreading that initiated 85–80 Ma in the south of the present Tasman Sea gradually rifted the new continent Zealandia from Eastern Gondwana, with rifting complete in the north by 60–55 Ma (Gaina et al., 1998, Schellart et al., 2006). The recent reconstructions by Strogen et al. (2023) developed these early models and in addition have a focus on land on Zealandia. They show Zealandia became fully separated from the Australian part of East Gondwana ca. 57 Ma although land connections had already been severed in the preceding few million years (Strogen et al., 2023). Thereafter, land area was progressively reduced, as the continent submerged, until the Late Oligocene marine highstand when ∼150,000 km2 remained (Strogen et al., 2023). Subsequently, land area increased, especially after the Australia–Pacific plate boundary migrated from its mid-Tasman Sea spreading centre to become propagated through New Zealand during the Early Miocene ∼18–16 Ma forming the Alpine Fault and resulting in regional uplift.

If only the authors of Genesis had been a little better informed about the real world and its history, they could have come up with at least a half plausible creation myth by including some of the fauna from distant lands from millions of years ago, even if they felt they had to include magic to explain a world they thought ran on it.

As it was, their parochial ignorance was about the worst imaginable preparation for the task, hence the laughable result that could only be believed by someone at least as parochially ignorant as they were.

Friday, 13 September 2024

Refuting Creationism - How Earth Became 'Fine-Tuned' For Death And Extinction


The synapsid Lystrosaurus survived the mass extinction and came to dominate the landscape later.

Julio Lacerda
September: El Nino | News and features | University of Bristol

Creationist claims that Earth was created perfectly designed for life (especially their life) are farcical and can only be believed by people carefully ignorant of the facts.

Of course, insisting that Earth is merely a few thousand years old, makes it easier to dismiss the 99.9975% of it that proves them wrong.

In my previous post I wrote about a newly-discovered trilobite with an additional pair of legs, and the reason we don't have them scuttling over marine sediment any more is because Earth turned against them when a climate catastrophe caused a marine catastrophe, depriving the oxygen-dependent organism's living in it of oxygen. This was one of the so-called Oceanic Deoxygenation Events.

That explains the mass extinction of marine life, but the question is, why did it also cause a terrestrial mass extinction of comparative severity?

Wednesday, 21 August 2024

Refuting Creationism - Not Whether But How And Where - Scientists Reassess The Fossil Record Of Human Evolution


A human evolutionary tree. The dashed lines indicate that evolutionary relationships between species are uncertain. Note the 'bushiness' of the tree; the australopithecine line branches into several species of Australopithecus and also to several Homo species

Fossil hotspots in Africa obscure a more complete picture of human evolution | Media Relations | The George Washington University

The Modern Theory of Evolution is not just an interpretation of the fossil record. It's not even an interpretation of the fossil record, but an explanation of the genetic, cladistic, physiological, anatomical and molecular evidence, all of which converge on the same explanation, supported by, but not dependent on, the fossil record.

That conclusion is species have evolved from earlier ancestors by a process of evolutionary divergence from common ancestors.

The problem of being too dependent on the fossil record, which is inevitable when the genetic, physiological and biochemical evidence is no longer available is that, because of the rarity of fossilisation which depends on a body finding itself in the right place at the right time, is that it is essentially a random sampling process which produces a snapshot of the population at that time and place, randomly placed both temporally and geographically.

With some places (and times) being more conducive to producing fossils, this snapshot can easily be biased in favour of particular places and times appearing to be more important to the evolutionary process than they were in reality. There are fossil hotspots because those places favoured fossilisation, not because more of the species were concentrated there or because something about that place influenced the evolution of the species.

Tuesday, 13 August 2024

Refuting Creationism - A strange Sea Slug - From 500 Million Years Before 'Creation Week'.


Spines covering the body of Shishania aculeata

Image credit: G Zhang/L Parry
August: Mollusc discovery | News and features | University of Bristol

Palaeontology has a habit of throwing up surprises.

Sadly for creationists, these surprises never show us that science is fundamentally wrong and creationism is fundamentally right. It invariably shows us exactly the opposite.

The surprise today is that an early mollusc resembled a slug with a spiky armour, not the smooth shell we normally associate with snails which were believed to have evolved in the Early Cambrian when this species lived.

The confirmation that creationism is fundamentally wrong comes from the fact that this strange slug lived in that very long pre-'Creation' period of Earth history, 500 million years before creationists think the Universe was magicked up out of nothing by some magic words spoken in a language that no-one else spoke because, so the story goes, there was no-one else for the magician to speak to.

The mollusc, named Shishania aculeata, was probably an early evolutionary dead-end; an early response to the threat to soft-bodies creatures from the emerging predators that gave the impetus for the rapid radiation of forms that characterised the Cambrian.

Friday, 9 August 2024

Refuting Creationism - The Mammoths Of Vancouver Island - Between 11,000 and 37,500 Or More Years Before 'Creation Week'


When mammoths roamed Vancouver Island: SFU and Royal BC Museum delve into beasts’ history in our region - SFU News - Simon Fraser University

There are no elephants in the Bible.

This news often comes as a shock to creationists brought up with fanciful drawings of pairs of animals walking up the gangplank onto a wooden boat in the childish tale of Noah and his Ark. Why? Weren't there a pair of elephants, as large as life, along with zebras, rhinos, hippos and penguins, according to the Bible?

Hmmm... LOL!
Well, no there weren't, for the simple reason that there is nothing in the Bible that wasn't known to the people who wrote the tale. Nothing outside a day or two's walk from the Canaanite Hills where they herded their goats and built their mud-brick dwellings, like any other Middle Eastern Bronze Age pastoralists.

And of course, although creationists will insist that the Bible records dinosaurs roaming the countryside at the time the tale was set, if you change the meanings of a few words, not only are elephants not mentioned, but nor are their ancient ancestors, the mammoths. And nor are continents like North and South America, Australia, Antarctica and of course islands like Vancouver, Greenland, Madagascar, Great Britain and Ireland were entirely unknown and unsuspected by the Bible's imaginative authors.

Which is why they imagined setting the beginnings of it all just a few thousand years earlier, made perfect sense. The entire history of Earth and life on it was as unknown to them as its geography and geology. These were simple people who lived on a flat, magical planet with a dome over it and who didn't know where the sun went at night, or that rain formed in clouds.

So how could they possibly have known about mammoths living on Vancouver Island in North America? It wasn't their fault that they were so poorly educated; they were probably about as well educated as any other Middle Eastern pastoralist of the Bronze Age - i.e., not very well at all, being illiterate and innumerate. The people who've let them down are the later cult leaders who collected their tales, bound them up in a book and decreed it to be the inerrant word of an omniscient god.

Weirdly, there are people alive today, in modern, technologically advanced countries, who believe what those ignorant goat-herders wrote has never been equaled, let alone bettered, by modern science, for its completeness, reliability and accuracy.

But there were mammoths living on Vancouver Island between 13,000 years and at least 35,000 years before the Bronze Age authors of the Bible set their creation myth to try to fill the gaps in their knowledge and understanding with narratives that made sense within their narrow framework of understanding, and this is how any rational person can tell the claims that the Bible was written of inspired by an omniscient creator god is nonsense - a dishonest fiction intended to deceive - false witnessing on a grand scale.

The evidence of these mammoths has just been published in the Canadian Journal of Earth Sciences and explained in a press release from Simon Fraser University. The authors examined 32 suspected mammoth samples from Vancouver Island, of which 16 proved suitable for carbon dating. One of the samples proved to be beyond the age at which 14C dating gives accurate results (45,000 years) so we only know that there were mammoths on Vancouver Island before 47,500 years ago.

Friday, 2 August 2024

Refuting Creationism - How Worms Turned - Into Insects


Fig. 1: Anatomical overview of Youti yuanshi.
Ancient worm fossil solves mystery of how insects and spiders evolved - Durham University

To anyone who has ever looked at the segmented body of an annelid worm and the segmented body of an insect, particularly in its larval stage, that the latter is really the former with legs and (usually as an adult) wings should be obvious. The same can be said for annelid worms and centipedes and, for that matter, worms with legs and arachnids (spiders, scorpions and mites). But maybe the connection between arachnids and crabs or insects and barnacles is not so obvious, until you look at how the legs work and how they both have an exoskeleton instead of an endoskeleton like the vertebrates.

But then even the primitive ancestors of the vertebrates were segmented like the annelids, as we can see in the spinal column and the way nerves arise from the spinal cord.

But, tell a creationist that a segmented worm evolved into the arthropods, and they'll immediately demand to see the 'transitional' fossil, that they've been fooled into thinking must exist because every generation of every species is obliged to leave a fossil so there is a complete, unbroken record of evolution somewhere, because the Theory of Evolution says so. In fact, a complete, unbroken fossil record of every generation of an evolving species over time would look suspiciously like something other than chance was at work in creating fossils.

So, what we have are the snapshots at random points in time that are left in the geological column, and various dating methods that tell us how old the fossil is. The rest is simple common sense and joining the dots.

And one such snapshot has just been announced by researchers working at Durham University, UK, who have identified a species that is clearly partway between a segmented worm and an early arthropod (euarthropod). The newly-named Youti yuanshi is about the size of a poppy seed and fits neatly into one of creationism's beloved gaps. And, of course, it is exactly what the TOE predicts should have lived, because, as I said, the connection between segmented worms and segmented arthropods is obvious.

Sunday, 21 July 2024

Refuting Creationism - The Bible Is Nonsense - So 42 Million-Year-Old Amber Tells Us


Rare parasitic wasp.
Maria Blake
Australian amber has revealed ‘living fossils’ traced back to Gondwana 42 million years ago

Amber is especially good for preserving in exquisite details, small arthropods which don't fossilise well in rocks, like larger vertebrates with hard body parts, and we can be confident that the age of the fossil is the age of the amber in which it is preserved.

Some years ago, on holiday in Kassandria, Greece, I came across a small group of Mediterranean pines that were being use to collect the resin used to flavour the local wine, Retsina. This wine is something of an acquired taste but is best drunk chilled, with Greek food, on a warm summer evening at sunset, overlooking the Aegean - and probably after a bottle or two of Demestica.

The fascinating thing was how many ants had managed to get themselves trapped in the resin in the plastic containers it was draining into from the cuts in the tree bark.

There were so many that I can only assume that when ancient amber was being produced there were either fewer ants or less resin.

So, what can we tell from the fossils preserved in amber?

Partly from their occurrence in amber, we know that some 85% of all living species were arthropods, rather than the 0.3% of species that were the much more noticeable vertebrates. We can also tell where and when major orders evolved and how long some of them have existed for. Since amber is formed from tree resin, it follows that it only occurred after trees evolved and from the resin produced by specific species of tree in areas where these trees grew.

Friday, 19 July 2024

Refuting Creationism - Evolution By Hybridization May Be Commonplace in Plants


The team found the black cottonwood-balsam poplar stable hybrid lineage after analyzing the genetic makeup of 546 poplar tree cuttings collected along seven transects ranging from Alaska to Wyoming, with collections in British Columbia and Alberta, Canada, in between.
Credit: Penn State. CC BY-NC-ND 4.0
Discovery of a hybrid lineage offers clues to how trees adapt to climate change | Penn State University

Despite creationist dogma that say otherwise, evolution in a population can occur hybridization, especially in plants, where it may be commonplace. Two related plants hybridize and the resulting offspring acquires additional genes which extend its capabilities, enabling it to survive environmental change or move into new niches, and forming a stable population with new allele frequencies.

And as though to rub salt into creationist wounds, some of these happened hundreds of thousands of years before creationism's legendary 'Creation Week', before which, on the say-so of some ignorant Bronze Age pastoralists who were unaware of anything more than a day or two's walk from the Canaanite Hills, creationists think there was once nothing out of which everything was created by some magic words, just a few thousand years ago.

They also hold the diametrically opposite views simultaneously, that evolution is impossible because the Second Law of Thermodynamics [sic] forbids it, and that evolution occurred as a massively accelerated rate in the last few thousand years, unnoticed by anyone, in which several whole new species arose in a single generation by magic.

Now a team led by Penn State University paleobotanists led by Associate Professor Jill Hamilton, from Penn State’s College of Agricultural Sciences, have shown that a hybrid between black cottonwood, or Populus trichocarpa, and balsam poplar, Populus balsamifera, was able to move out of the wet coastal region to which most black cottonwood trees are restricted, into the arid lands to the east. This movement started about 800,000 years ago.

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