Jurassic Park Period Part 4

Fauna - Reptiles

During the Jurassic, dinosaurs came to dominate the animal world, but they were not the only type of animals. The first birds appeared, evolving from a branch of theropod (hollow-boned) dinosaurs, to share the skies with pterosaurs, the dominant flying vertebrates. Lizards made an appearance and have been with us ever since. Therian mammals evolved, meaning creatures that gave birth to live young, and that includes marsupials. Crocodylomorphs (which eventually gave rise to modern crocodylia, but not during the Jurassic) transitioned from a terrestrial to an aquatic life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs.

This is a lot of ground to cover (so to speak), so I'm going to start in the oceans and work my way to land and sky.

The Triassic/Jurassic extinction event decimated crocodile-like reptilian diversity, with crocodylomorphs (which originated during the last half of the Triassic) being the only group to survive. Even the herbivorous aetosaurs died out. [Can you imagine if they had survived, and we had vegetarian crocodiles raiding our gardens?] The diversity of crocodylomorphs during the Early Jurassic was about the same as those of the Late Triassic, but they occupied different ecological niches.

A group of predominantly marine crocodylomorphs became a prominent part of marine ecosystems. Within that group, some became highly adapted for life in the open ocean, including the transformation of limbs into flippers, the development of a tail fluke, and smooth, scaleless skin.

Turtles - Turtles (Testudinata) diversified during the Jurassic. The Jurassic turtles are believed to have formed 2 more advanced groups, the Mesochelydia (which were aquatic), and the Perichelydia. There are 2 modern groups turtles (the Testudines), which are terrestrial and had diverged by the Middle Jurassic. The Thalassochelydia is a diverse lineage of sea turtles, and is known from the Late Jurassic of Europe and South America.

Lepidosaurs - The tuatara is a reptile native only to New Zealand, and is the sole living representative of the Rhynchocephalians, which had achieved a global distribution by the beginning of the Jurassic. The Rhynchocephalians occupied a wide range of lifestyles, including the aquatic pleurosaurs with long snake-like bodies and reduced limbs, the herbivorous eilenodontines, and the Oenosaurus, which had broad tooth plates indicative that they ate creatures that were hard-shelled or had an exo-skeleton, such as corals, shelled mollusks and crabs. Rhynochocephalians disappeared from Asia after the Early Jurassic. The last common ancestor of living squamates (which includes lizards and snakes) is estimated to have lived around 190 million years ago during the Early Jurassic. Squamates first appear in the fossil record during the Middle Jurassic and included early members of a snake lineage. However, many Jurassic squamates have unclear relationships to living groups. Eichstaettisaurus from the Late Jurassic of Germany has been suggested to be an early relative of geckos and displays adaptations for climbing.

Ichthyosaurs - The Ichthyosaurs suffered an evolutionary bottleneck during the Triassic/Jurassic extinction event, with all but one group of them becoming extinct. Ichthyosaurs reached its apex of species diversity during the Early Jurassic, including the huge apex predator Temnodontosaurus and the swordfish-like Eurhinosaurus. However, Early Jurassic ichthyosaurs were significantly less morphologically diverse than their Triassic counterparts

Plesiosaurs - The Plesiosaurs originated at the end of the Triassic Period. At least 6 lineages of plesiosaur crossed the Triassic-Jurassic boundary, so they were already diverse in the Earliest Jurassic. Early plesiosaurs were generally small-bodied, with body size increasing later. There appears to have been a strong turnover as the middle of the Jurassic Period began, with the extinction of 2 groups that had been widespread, and the first appearance of the Cryptoclididae group, which became the dominant group of the latter half of the Jurassic. During this time, the thalassophonean pliosaurs, which had ancestrally been small-headed and long-necked, evolved short necks and large heads. Some species, such as the Pliosaurus, had skulls up to 2 metres (6 ft) in length, with body lengths estimated around 10-12 meters (30-36 feet), making them the apex predators of Late Jurassic oceans. Small-bodied plesiosaurs also invaded freshwater environments during the Jurassic, as shown by remains found in freshwater sediments from China and Australia.

Pterosaurs - Pterosaurs first appeared in the Late Triassic, but a major group of Jurassic pterosaurs is the Rhamphorhynchidae, which first appeared in the Early Jurassic. They ate fish. Another group, the Anurognathids, first appeared in the Middle Jurassic. They had short heads and densely furred bodies, and were probably insectivores. Short-tailed pterodactyloids first appeared in the at the beginning of the Late Jurassic. These include the ctenochasmatids, which have closely spaced needle-like teeth that were presumably used for filter feeding. The Late Jurassic Cycnorhamphus had a jaw with teeth only at the tips, with bent jaws like those of living openbill storks, that may have been used to hold and crush hard invertebrates.

Some of these animals could be found on land, as indicated in the above paragraphs by what they ate. But I'm fairly confident that they had branches of relatives living in the oceans. I am sorry for the use of huge tongue-twisting names, but there were so many names, I would have gotten completely bogged down trying to describe the various species.

There you have some of the reptiles that lived in the oceans and other waterways. This has been a long post, so I am going to end it here and take up fish next time. Yes, there were fish in the waters, too.

There will not be a quiz on the names used in this blog. Class dismissed.

https://en.wikipedia.org/wiki/Jurassic

https://en.wikipedia.org/wiki/Crocodylomorpha

Jurassic Park Period Part 2

Paleoclimate

Climate during the Jurassic was approximately 5-10 degrees C (41-50 degrees F) hotter than present time, with atmospheric carbon dioxide likely 4 times higher. It's likely that forests grew near the poles, where they experienced warm summers and cold, sometimes snowy winters. It is unlikely there were any ice sheets, as the high summer temperatures would have prevented the accumulation of snow, although there may have been mountain glaciers. The ocean depths were likely 8 degrees C (about 46 degrees F) warmer than present, and coral reefs grew further north and south by 10 degrees of latitude There were probably large areas of desert in the lower latitudes.

The beginning of the Jurassic was probably marked by a thermal spike corresponding to the eruption of the Central Atlantic magmatic province. This was followed by the Early Jurassic cool interval between 199 and 183 million years ago. ('Cool', of course, is a relative term.) Then came a spike in global temperatures of around 4-8 degrees C (39-46 degrees F) during the eruption of the Karoo-Ferrar large igneous provinces in southern Gondwana, which lasted from 183 million years ago until 174 million years ago.

During this long temperature spike, the ocean surface temperatures likely exceeded 30°C (86°F) and all the land mass between 30°N to 30°C were likely extremely arid, with temperatures in the interior in excess of 40°C (104°F).

There was an episode of widespread oceanic anoxia that is often attributed to the eruption of the Karoo-Ferrar large igneous provinces and the associated increase of carbon dioxide concentration in the atmosphere. This event had significant impact on marine invertebrates, but little effect on marine reptiles. During this time, the Sichuan Basin (of southwestern China) was transformed into a giant lake, 3 times the size of Lake Superior. Seawater pH dropped to its lowest point around the middle of this event.

This was followed by a (relatively) cool period between 174 and 164 million years ago, which was followed by a warm interval between 164 and 150 million years ago. During this warm interval, the land mass interior had less severe seasonal swings than before because the expansion of the Central Atlantic and the western Indian Oceans provided new sources of moisture to moderate the temperature. The end of the Jurassic was marked by another cool interval, which began 150 million years ago and continued beyond the end of the Jurassic.

I recently saw someone on social media poo-pooing concern over the climate changing. As they put it, the climate has been changing for millions of years. And they are right, it has been. What they fail to take into consideration is that mass extinction events have been happening for millions of years, AND the climate changes of the past have not occurred as rapidly as this one. If we want to survive this climate change, we need to use the brains we have.

https://en.wikipedia.org/wiki/Jurassic

Triassic Period Part 1

 The Triassic Period spans 50.6 million years, from 251.9 million years ago to 201.4 million years ago. It is the first and shortest period of the Mesozoic Era. It both started and ended with a major extinction event.

The Permian–Triassic extinction devastated terrestrial life. Diverse communities with complex food-web structures took 30 million years to reestablish.

The Triassic period ended with a mass extinction which was particularly severe in the oceans. All the marine reptiles disappeared except for the ichthyosaurs and plesiosaurs. Invertebrates like molluscs were severely affected. In the oceans, 22% of marine families and possibly half of marine genera went missing.

The vast supercontinent of Pangaea continued until the mid-Triassic, after which it began to gradually split into two separate landmasses, Laurasia to the north and Gondwana to the south.

During this time period, almost all the Earth's land mass was concentrated into a single supercontinent centered more or less on the equator and spanning from pole to pole. The Tethys Sea penetrated the east side of this continent for a good distance along the equator. There was an older branch of the ocean (called the Paleo-Tethys Ocean) north of the Tethys Sea that was now closed off by a group of moving islands that became a strip of land.

During the mid-Triassic, a similar sea penetrated along the equator from the west coast. This sea was not named in the article I read. All the rest of Pangaea's shores were surrounded by the world-ocean known as Panthalassa. Although it was not stated, my guess is that these 2 long seas coming from the east and the west along the equator finally met, and Pangaea was no more.

The sea level was consistently low compared to the other geological periods. The beginning of the Triassic saw the sea level at around present sea level, rising to about 10-20 m (30-60 ft) above sea level during the Early and Middle Triassic. Then the sea level began to rise, with it reaching up to 50 metres (150 ft) above the present sea level. It then began to decline, reaching a low of 50 metres below the present sea level, which continued into the next time period.

The global climate during the Triassic was mostly hot and dry, with deserts spanning much of Pangaea's interior. There is no evidence of glaciation at or near either pole. In fact, the polar regions were apparently moist and temperate, providing a climate suitable for forests and vertebrates, including reptiles. Pangaea's large size limited the moderating effect of the global ocean; it's continental climate was highly seasonal, with very hot summers and cold winters. The strong contrast between Pangea and the global ocean triggered intense monsoons.

The climate shifted and became more humid as Pangaea began to split apart. The Triassic may have mostly been a dry period, but evidence exists that it was punctuated by several episodes of increased rainfall in tropical and subtropical latitudes of the Tethys Sea and its surrounding land. It may be that volcanic activity helped trigger climate change during this period.

Next we'll take a look at the inhabitants of Earth during the Triassic Period.

https://en.wikipedia.org/wiki/Triassic

Mesozoic Era

 Okay, we're going to take a quick overview look at the Mesozoic Era, also known as the Age of Reptiles. It lasted from 252 to 66 million years ago. It has 3 Periods nestled within it; the Triassic, Jurassic and Cretaceous periods. It was characterized by dinosaurs, conifers and ferns, a hot greenhouse climate, and the tectonic break-up of Pangaea.

The Mesozoic began just after the largest well-documented mass extinction in Earth's history, and it ended with another extinction event.

During this era, the supercontinent Pangaea broke into separate landmasses that would eventually move into their current positions during the following era. There was not much mountain building during this era, but what little did occur took place around what is now known as the Arctic Ocean. In contrast, the supercontinent Pangaea gradually split into a northern continent, Laurasia, and a southern continent, Gondwana. (Seems like this name has been used before.) By the end of the era, the continents had split up and some had rejoined into their present forms, though not their present positions. Laurasia became North America and Eurasia, while Gondwana split into South America, Africa, Australia, Antarctica and the Indian subcontinent, which would eventually slam into Asia, giving rise to the Himalayas, but not during this Era.

The climate varied, alternating between warm and cool periods. Overall, the Earth was hotter than it is today. The Triassic (first) Period was generally dry and highly seasonal, especially in Pangaea's interior. Low sea levels would have exacerbated temperature extremes. Pangaea's interior probably included expansive deserts.

Sea levels began to rise during the Jurassic (second) Period, most likely caused by seafloor spreading. The sea levels could have risen as much as 656 ft (200 m) above today's sea level. This would have flooded coastal area. In addition, the breaking up of Gondwana into smaller continents created new shorelines. Temperatures continued to increase for a time, then began to stabilize. With the proximity of water, humidity also increased, and the deserts retreated.

The climate of the Cretaceous (third) Period is more widely disputed. Probably, higher levels of carbon dioxide in the atmosphere could have almost eliminated the north-south temperature gradient, meaning that temperatures were about the same across the planet, about 10 degrees Centigrade higher than today.

Dinosaurs first appeared mid-way through the first period, and became the dominant terrestrial vertebrates by early in the second period, then died out at the end of the third period. Archaic birds appeared during the 2nd period (Jurassic), evolving from a branch of dinosaurs. True birds appeared in the third period. Mammals also appeared during this era, but they remained small (less than 33 lb) until the third period. Flowering plants appeared early in the third period and rapidly diversified, replacing conifers and other gymnosperms as the dominant group of plants. But we'll take a closer look at flora and fauna as we get to those periods.

 

https://en.wikipedia.org/wiki/Mesozoic

Ordovician Period

When I first started reading the article on the Ordovician Period, I got to the mention of Gondwana, which made me stop and wonder, "Wait, haven't we been through this breakup before?" And the answer is yes, we have, in the blog I wrote about the Paleozoic Era, which the Ordovician Period is part of. I had to remind myself that this is not really déjà vue, that the Paleozoic Era has 6 periods to it, and my blog on the Era would have been like an overview, while the blogs on the periods would have more details. So, some of the big events, like the breakup of Gondwana, will be mentioned in both posts.

The Ordovician Period spans 41.6 million years, from the end on the Cambrian Period some 485.4 million years ago to 443.6 million years ago.

Life continued to flourish during the Ordovician Period, although there was an extinction event at the end of the period. The Ordovician Period is known for its biodiversification event, which considerably increased the diversity of life. Invertebrates, namely molluscs and arthropods, dominated the oceans, although fish, the world's first true vertebrates, continued to evolve, and fish with jaws may have first appeared late in the period. Life on land had yet to diversify.

However many meteorites strike the Earth in a year today, there were 100 times that many hitting the Earth per year during this period.

The southern continents were collected into Gondwana, which started the period in equatorial latitudes but then drifted toward the South Pole. Meanwhile, other continents, Laurentia (part of North American), Siberia, and Baltica (northern Europe), were drifting north, and Baltica started moving towards Laurentia later in the period. Another small continent, Avalonia, separated from Gondwana and began moving north towards Baltica and Laurentia.

Temperatures were mild in the early and middle Ordovician Period, but from 460-450 million years ago, volcanoes along one of the oceans spewed massive amounts of carbon dioxide (a greenhouse gas) into the atmosphere, turning the planet into a hothouse. These volcanic island arcs eventually collided with proto-North America and formed the Appalachian Mountains. [At last! I've been waiting for billions of years for the Appalachians to appear!]

Initially, sea levels were high, but as Gondwana moved south, ice accumulated into glaciers and the sea levels dropped. At first, low-lying sea beds increased diversity, but later glaciation led to mass extinctions as the seas drained and continental shelves became dry land. By the end of the period, the volcanic emissions had stopped. By then, Gondwana had neared the South Pole and was largely glaciated.

Reef-forming corals first appeared early in this period. Land plants probably evolved from green algae, first appearing in a form resembling liverworts. Fungi was also an early adopter of living on land, and facilitated the colonization of land by making mineral nutrients available to plant cells.

This period closed with a series of extinction events that are generally regarded as one major event, in which 49% of all fauna died. It is generally agreed that this event or series of events were caused by an ice age. That ice age had several pulses of increasing/decreasing glaciation. Each time the glaciation increased, the sea level dropped, killing many of the fauna that inhabited the shallow seas. When the sea levels rose during the next decrease of glaciation, there were entire families of fauna that had not survived to re-establish themselves in the shallow seas. This may have happened several times, producing a series of extinction events.

Well, now we're starting to get some place. Plants (of sorts) on land, starting to make the soil arable. Not sure about the carbon dioxide level in the atmosphere, but the meteor showers would be beautiful, as long as they didn't land too close. Hunting probably wouldn't do much good yet, but, hey, there's fish! Too bad I can't stand fish.

Maybe the next period will be even more amenable?

 

https://en.wikipedia.org/wiki/Ordovician 

Cambrian Period

 The Cambrian Period was the first geological period of the Paleozoic Era. It lasted 55.6 million years, from 541 million years ago to 485.4 million years ago. The Cambrian is known for sites of exceptional preservation where even 'soft' parts of organisms are preserved, so our understanding of the Cambrian biology surpasses that of some later periods.

A profound change in life on Earth happened during the Cambrian Period, in that mineralized multicellular organisms became common. The rapid diversification of life-forms in this period—known as the Cambrian Explosion—produced the first representatives of all modern animals, probably from a single common ancestor.

Although life prospered in the oceans, the land is thought to have been comparatively barren. Shallow seas flanked several continents and were relatively warm. Polar ice was absent for much of the period.

Large, high-velocity rotational movement of Gondwana appears to have occurred in the early Cambrian, and may have resulted in Laurentia (North America), Baltica and Siberia being 'tossed away' and forming isolated land masses. Most continental land was clustered in the Southern Hemisphere, but was drifting north.

With a lack of sea ice, the sea level was high, which led to large areas of the continents being flooded in warm shallow seas, which were ideal for sea life. The sea levels fluctuated, suggesting there were pulses of expansion and contraction of a south polar ice cap.

The article stated that the Earth was generally cold during the early Cambrian, and then said the average temperatures were 7 degrees Celsius higher than today. That doesn't seem very cold to me.

The Cambrian flora was little different from what had existed in the previous period. Primarily, there were marine macroalgae in the seas, and that was pretty much it. There were no land plants known from the Cambrian, although biofilms and microbial mats were well developed on tidal flats and beaches 500 million years ago. There were also microbes forming microbial Earth ecosystems, comparable with modern soil crust of desserts, which contributed to soil formation.

It was once thought that trilobites were the dominant life form of the time period. But it turns out that these had a heavy armor which fossilized far more easily than the bodies of other animals, so there were plenty of trilobite fossils, even though trilobites were only a minor part of the animal diversity.

Earth suffered a mass extinction at the start of the Cambrian Period. It is thought that animals that burrowed into the sea bed, destroyed the microbial mats covering the seabed, and many organisms dependent on the mats became extinct, while other species adapted to the changed environment.

Despite the 'Explosion' at the start of this period, the later half saw a sharp drop in biodiversity. 500 million years ago, oxygen levels in the oceans dropped dramatically, while the level of poisonous hydrogen sulfide increased, producing more extinction events, making the latter half of the period surprisingly barren.

However, some organisms did venture onto land, producing trace fossils of their movements. Some of these fossil trackways suggest a large, slug-like mollusc.

Just when you thought Earth pre-history was going to get interesting, it takes one step forward and two steps back. Dry land is still pretty barren, except for an occasional slug-mollusc looking for some tasty soil microbes.

Well, we're pretty sure humans arrive on the scene eventually, so we're just going to keep slogging forward until we find us.

 

https://en.wikipedia.org/wiki/Cambrian

Archaen Eon

 

The Archean Eon is the second of the four geologic eons of Earth’s history. (The first was Hadean Eon.) During the Archaen Eon, which lasted roughly 4,000 to 2,500 million years ago, the Earth’s crust cooled enough to allow the formation of continents and the beginning of life on Earth. Sounds like a busy time, doesn’t it?

The oldest rock formations on Earth’s surface are Archean. They are found in Greenland, Siberia, Canada, Montana, Wyoming, Scotland, India, Brazil, western Australia and southern Africa, as well as other regions. Volcanic activity was much higher than it is today, producing many different kind of volcanic rocks.

The continents started to form during the Archean, although details are still being debated.  Although this is when the first continents formed, rock of this ages makes up only 7% of the present world’s land mass. Allowing for erosion and destruction of past formations suggests that only 5-40% of the present area of continents formed during the Archean Eon.

By the end of the Archean, plate tectonic activity may have been similar to that of the modern Earth. For those who know how to read it, evidence demonstrates that liquid water was prevalent and deep oceanic basins already existed.

The Archean atmosphere had very little free oxygen, yet temperatures appear to have been near modern levels. The moderate temperatures may be because of greater amounts of greenhouse gases. Or, the Earth may have reflected less sunlight and heat due to having less land area.

There is substantial evidence that life began either near the end of the Hadean Eon or early in the Archean Eon.

The earliest identifiable fossils consist of stromatolites, which are microbial mats formed in shallow water by cyanobacteria. The earliest were found to be 3.48 billion years old. They were found throughout the Archean and became common late in the Eon. Cyanobacteria were instrumental in creating free oxygen in the atmosphere, and created so much of it that later, there was a crisis of sorts, when the life that existed at the time could not cope with the high level of oxygen. (I read that somewhere and have included it in one of my other blogs, but at this time, I can’t remember where I got that from.)

It is generally agreed that before the Archean Eon, life as we know it would have been severely challenged by the hostile environmental conditions then found on Earth.

Life during the Archean consisted of simple single-celled organisms such as Bacteria.

However, fossilized microbes from terrestrial microbial mats show that life was already established on land as long ago as 3.22 billion years.

So, it was a busy time. Lots of water sloshing around, lots of volcanoes creating land masses, and life beginning to get a first grasp on the place. If we wound up crash-landing on a planet like that, could we survive? Could we cultivate cyanobacteria to create more oxygen for us? Doing that to any large extent might strip out some of the greenhouse gases, which could lower the temperature of the planet. Which only goes to show that you have to be careful what you do to make a place your home.

 

https://en.wikipedia.org/wiki/Archean#:~:text=The%20Archean%20Eon%20(%20%2F%C9%91%CB%90r%CB%88,beginning%20of%20life%20on%20Earth.

Whale Ancestors

Where did whales come from? How did a fish evolve to become as large as a modern whale?

Actually, whales took a round-about route to evolve into today’s huge ocean creatures. They are actually descended from a land animal.

There are plenty of clues in a whale’s body and biology that their ancestors lived on land:

* They breathe air.

* They nurse their young with their own milk.

* Their paddle-shaped flippers encase hand bones with five ‘fingers’.

* As embryos, whales have tiny back limbs which disappear before birth.

It turns out that hippos are the closest living relatives of whales, but not their ancestors. Both hippos and whales evolved from four-legged, even-toed, hoofed ancestors that lived on land about 50 million years ago. The hippo’s ancestor stayed on land, but the whale ancestor—which was about the size of a goat—moved to the sea and evolved into swimming creatures over a period of about 8 million years, which is quite fast for evolutionary processes.

When fossils of gigantic ancient whales were first discovered, they were mistaken for dinosaur fossils and given the name Basilosaurus. But later, they were recognized as mammals. These prehistoric whales were more elongated than modern whales and had small back legs and front flippers. Their nostrils were situated halfway between the tip of the snout and the forehead. They had earbones just like those of modern whales. Therefore, Basilosaurus showed the link between whales and their terrestrial ancestor.

The current theory is this: That some land-living hoofed animals favoured the flavor of plants at the water’s edge. Eating them had the added advantage of allowing them to easily hide from danger in shallow water. Over time, their descendants spent more and more time in the water, possibly in an ancient estuary, and their bodies became adapted for swimming. The front legs became flippers. A thick layer of fat called blubber replaced their fur coats to keep them warm and streamlined. Their tails became bigger and stronger for powerful swimming, and their back legs shrunk. Their nostrils gradually moved to the top of their heads so that they could breathe easily without having to tilt their heads while swimming. As these creatures began to feed on a different diet, they lost their teeth in favor of a baleen filter method of feeding.

Between these articles, there was some disagreement about what whale ancestors ate. One stated that they favored plants found at the water’s edge. Another felt they ate small land animals and fish found close to shore. Neither article had any information on the teeth whale ancestors had, so their eating preferences seem pretty much up in the air.

So, what can we learn from this tale of whales? Be careful what and where you eat? Evolution is your friend? I find myself wondering if whales would ever come back out of the water, what would they evolve to then? Some version of a goat-sized, hoofed animal again? One of the articles did mention that occasionally, a whale comes along that does have vestigial back legs that are completely encased within their body. Therefore, it seems possible that back legs could make a comeback.

Come on, work with me here. If octopuses can come out of the ocean and become a terrestial bad guy, as some scientists seem to think, then surely whales can also emerge from the oceans. Given enough time to evolve.

 

https://us.whales.org/whales-dolphins/how-did-whales-evolve/

https://evolution.berkeley.edu/evolibrary/article/evograms_03

https://www.nhm.ac.uk/discover/when-whales-walked-on-four-legs.html

Cambrian Period

The Cambrian Period lasted from 541 to 485 million years ago. At the beginning of this time period, the small unicellulars that represented most life on Earth became more complex and multicellular. They also diversified quite rapidly, bringing forth the first representatives of all modern animal phyla. Indeed, there is strong evidence that all animals evolved from a single common ancestor.

Life prospered in the oceans, but the land is thought to have been relatively barren, with nothing more complex than a microbial soil crust or biofilm. A few molluscs may have emerged to browse on that biofilm, but the continents were probably dry and rocky. The global supercontinent Pannotia had just broken up during the early part of the period, and the new continents were mostly flanked by shallow seas, which were relatively warm. Polar ice was absent for much of this period.

Most land masses were clustered in the Southern Hemisphere during this period, but were drifting north. During the early portion of the Cambrian, the supercontinent of Gondwana went through some large, high-velocity rotational movements.

Trilobites (I wrote about them in an earlier post) were rampant during the Cambrian period. Possibly this was because without any sea ice, the sea level was high, which meant large areas of the continents were flooded in warm shallow seas, which is ideal for sea live. But the sea levels did fluctuate somewhat, suggesting there were ‘ice ages’, possibly meaning pulses of expansion and contraction of a south polar ice cap. Although the beginning of the period was cold, the average temperature during the Cambrian was 7° Celsius warmer than today.

Even so, trilobites were not the dominant species, as was once thought. It seemed they were, because they had hard external shells that were easy to fossilize, much easier than the thin chitinous shells of other arthropods, and so trilobite fossils were much easier to find by today’s paleontologists.

The Cambrian period is often referred to as ‘the Cambrian Explosion’, indicating a huge increase in the variety and diversity of life forms. But it seems (to me) that it might be better to think of it as ‘the Period of Great Changes’. At the start of the Cambrian, new creatures with new behaviors and lifestyles destroyed the biofilm that covered the sea floor, so all the creatures (from the previous time period) who depended on that biofilm died out.

Around 515 million years ago, the number of species dying out was larger than the number of new species coming into existence. 500 million years ago, the oceans saw a big drop in the oxygen content, and at the same time, the level of toxic hydrogen sulfide increased. Either of these events alone could produce extinctions, so imagine what happened when they came in together.

Where would hydrogen sulfide have come from? There are a few ways nature makes it, including anerobic digestion by certain biofilms in the absence of oxygen. I can’t rule that one out, but I’m somewhat more inclined to ‘blame’ volcanoes, which also produce it, probably in larger quantities and certainly can do it in oceans. Also, the heat given off by the volcano(es) would tend to drive oxygen out of the water. So, was there a series of huge volcano events 500 million years ago? I don’t know. It seems possible.

And there we have the Cambrian period in a nutshell. No fascinating dinosaurs to study, but the thought of a spinning Gondwana certainly has my attention.

https://en.wikipedia.org/wiki/Cambrian

https://en.wikipedia.org/wiki/Hydrogen_sulfide

The Sky is Falling

If you follow me on facebook, you may have noticed that I have shared many articles on climate change and that I have started using the comment, “The Sky is Falling.”

It seemed more appropriate than saying, “The Boy Cried Wolf.” In that story, the boy is lying, only looking to introduce some excitement into his own life, without regard for the consequences.

Chicken Little, on the other hand, was telling the truth, as best he knew it. Something (a raindrop) had come down from the sky and hit him. He had never experienced anything like that before, so the logical conclusion was that something terrible was happening, the sky was falling! Chicken Little ran around the farmyard squawking his terrible news, trying to warn all the other farm critters.

Even that doesn’t exactly fit the problem of climate change. Chicken Little was very young and inexperienced. But it’s scientists who have been trying to warn the world’s population that the climate was changing far quicker than it should. They have lots of experience at studying climate and how it has changed in the past, and they have a pretty darn good idea where it’s headed.

In the past week, I have read several articles concerning the number and severity of heatwaves that have been happening around the world. Not only has the world been having more of them, not only have they broken records for daytime high temperatures, they’ve broken records for the highest low temperatures as well. That means that after a sweltering day, you don’t get much relief during the night, because the heat that has accumulated all day doesn’t dissipate fast enough.

I think Europe has already broken several summer records during a heatwave in June of this year. There’s no guarantee they won’t have another later this summer. Or this fall, or... whenever. A heatwave can happen at any time on the calendar, because it is a comparison between the present and what has been ‘normal’ previously.

The scientists don’t ‘think’ any particular place will start having a heatwave every year. But it could happen. After all, they wanted us to keep the warming of the Earth to 2°C or less. What are they saying now, that it’s officially reached a warming of 1.8°C? But in Europe, the temperatures reached +4 to +8°C over ‘normal’.

I don’t know about you, but I don’t get much done when the temperature gets to 95°F. I sure don’t want it to consistently reach 123°F. Or higher.

Maybe Chicken Little isn’t the best story for me to quote to try to get my point across, but it’s the one I can remember as the summer heat settles in. So I’ll keep squawking my warning and hope somebody is listening, because...

The sky is falling.

Trilobite, Do You Bite in Threes?

When you spend a lot of time as a child/teen/adult reading everything you can find on all those fascinating creatures that inhabited the Earth before Humans came along, you come across a lot of strange names. You aren’t sure what those names mean. You might have a rough idea what that type of creature looked like, and that’s probably about all that you know. Because, really, who cares about an extinct sea creature that looked like some crazy kind of beetle?

So I decided to see what I could find out about trilobites, see if there was something about them that would prove interesting. I headed for Wikipedia to get a smattering of layman information before I looked for more advanced info.

Wow. The first sentence in the Wikipedia article is (basicly) “Trilobites ... are a group of extinct marine arachnomorph arthropods that form the class Trilobita. Guess we’d better put on our thinking caps for this one!

Extinct = they are all dead.

Marine = lived in the sea. Or maybe lived in water.

Arachnomorph = ? Well, arachnid is a type of spider, scorpions and what have you. (Thanks, dictionary.com, but why don’t you have the entire word in your list?) Morph has more than one meaning, but the one I’m most familiar with is “to transform”.

Arthropod = an invertebrate with a segmented body, jointed limbs and usually a hard shell that can be molted (discarded) should the creature get too big for it.

So far, what we’ve got is a water creature with a segmented body, limbs with joints and a hard shell. Might have looked vaguely like a spider. What comes to mind is a lobster, but they didn’t really look like that. The most common rendition I’ve seen for a trilobite is an oval shape. The larger ‘end’ is a pretty solid ‘half moon’ shape, with a ‘tail’ that goes down the middle of the oval to the smaller ‘end’. Behind the half moon head and on either side of the tail, filling up all the rest of the oval, are lots of limbs. But other trilobites had much different shapes. Let’s go on; what more can I find?

Trilobites ranged from 1/10 of an inch to about 12 inches. I think that entire range is for adult specimen.

The last of the trilobites died about 252 million years ago. But before that, they were quite a successful species, having spread all around the world and existing for over 300 million years. Scientists believe trilobites started their long journey as much as 700 million years ago, or possibly even further back. And if you think humans have some wildly different lifestyles, you obviously have not met many trilobites. Some were aggressive, and moved over the sea bed as predators, scavengers and/or filter feeders. Others were less aggressive and swam while eating plankton. Scientists are still debating whether or not any trilobites were parasites, while one group of trilobites appear to have had a symbiotic relationship with sulfur-eating bacteria.

Trilobites are thought to have originated in what is now Siberia. But that was over half a billion years ago, and with plate tectonics, who knows where that was actually located? Well, I’m sure there are people who do know, but I don’t. I’m going to have to look it up. Look for it in a later episode.

Anyway, as I said before, the trilobites all died out. Although they seemed to excel in changing shape, habitat and food throughout their long existence, eventually there was only one family left, and when its habitat disappeared, so did they. But while they were here, there were thousands of variations of trilobite. This diversity helped them fill many niches in the cycle of life.

On the other hand, there are some very distant relatives of the trilobites still living on Earth. Think horseshoe crab and others of that ilk.

And that is all I found that I understood in this 29-page article on Wikipedia. Go ahead and read it, if you want, but I warn you, it is FULL of very long words, most of them names of genus, family and specie, but not all. The ones that aren’t are used generously, with no explanation what it refers to, and which may not be in your dictionary. Have fun!

https://en.wikipedia.org/wiki/Trilobite

What is This World Coming to? 5

Okay, I did find something to say on this subject, from a totally unexpected source. I was watching an episode on Nova the other night. Our local channel has 2 episodes on Wednesdays, and we usually watch the first, but not the second, because that’s getting too late for my husband, who is an early bird. That night, I heard that the 2nd episode was on Neanderthals, and human evolution has always been an interest of mine, so I stayed up to watch it.

As a whole, the episode explored a lot of different information about the humans known as Neanderthals, but my interest picked up during their talk about the small colony of Neanderthals who lived in caves currently located at the base of the Rock of Gibraltar.

One question this episode was asking is, “Did Modern Humans have any part in eliminating the Neanderthals?” They didn’t have an answer to that question, in the end. Not a simple one, anyway.

Neanderthals lived in the Middle East, Western Asia and Europe for as much as 700,000 years. During all of that time, the world was in an ice age, but the Neanderthals were built for it, and apparently did not find that a hardship.

About 100,000 years ago (maybe as early as 125,000 years ago), modern humans started to populate these same areas. The cold probably made them wear more clothes than the Neanderthals. And maybe there were instances of violence between the 2 sub-species.

However, the scientists said, it was unlikely the modern humans had traveled all the way around the Mediterranean Sea and got to the Rock of Gibraltar before that particular group of Neanderthals died out. What the scientists discovered in those caves showed that the Neanderthals living there not only hunted and gathered, they ate a variety of sea life as well, from seals to clams. Today, the mouths of those caves are practically at the sea line, but during the brunt of the ice age, the water line would have been about 59 feet (18 meters) lower.

Neanderthals lived in small groups. Scientists estimate their entire population may have been about 100,000, scattered in small groups across a quarter of the world. (How big is the town you live in?) And as they studied this particular group, they realized that it died out during a long and severe drought that hit the area.

My thought? Neanderthals were suited for cold. Not so much for heat. They had a short, stocky build that would help them retain body heat. But when the world heats up, that doesn’t do you much good.

If the world were going through the gradual changes of leaving the ice age, the flora and fauna would no doubt evolve in order to survive. But the current rapid pace of warming that we are in doesn’t leave us time for that. Those who currently live in the tropics might manage by migrating north or south to the temperate zones. Those in the temperate zones might find some comfort in the polar regions, although there’s not a lot of land for them to settle on. Once Antarctica thaws, that land would be available. Would it be fertile? Who knows?

It won’t be a matter of the fit being able to survive. Those who can accept what’s happening and deal with it will have a chance to survive.

And I’m back to looking for potential food for that migrating population.

What is This World Coming to? 3

So, what else is the Beaufort Gyre (which, you’ll remember, is north of Alaska) doing to The World As We Know It?

Well, it’s messing up the Arctic jet stream. Being from the midwest US, I’ve heard plenty of winter weather forecasts talking about the Arctic jet stream dipping below the Canadian border and bringing truly frigid blasts to the North American plains. Since I still have friends and family living in that region, I pay attention to the winter weather that happens there. Last year was particularly brutal, with that jet stream going much further south than I remember it doing in the past. It wasn’t just the northern states like the Dakotas, Michigan and maybe Nebraska hunkering down against Arctic-type temperatures, they were reaching into Kansas, Missouri, Illinois, Indiana...

How can that possibly mean the climate is warming? Let me remind you that climate and weather are not the same thing. Weather happens on a much smaller scale than climate. As for that Arctic jet stream coming south before returning north, that air gets (relatively) warmed up. Coming so far south, it gets a lot warmer than it normally does, so when it does go north again, it transfers the warmth it gathered to the area it goes; the arctic. More melting.

Earth’s polar ice caps serve a purpose; sunlight is reflected from their white surface, so they act as a ‘cooling’ agent for the entire globe. The more this ice melts and reveals darker-colored water and land, the less cooling is available for the entire planet. Get it? The more snow and ice melts, the more likely more snow and ice will melt. Until there is no more snow and ice to help keep Earth’s temperature moderated.

The really scary part is what happens to the land when all that snow and ice melts. If Greenland’s ice cap melts, the sea level would rise by 20 feet (6.1 m). At its current rate of melt, the Arctic Ocean could be completely ice free by 2040. That’s only 22 years! If all the ice of Antarctica melted, the seas would rise by 200 ft (61 m).

With a sea level rise of only 6 feet (1.8 m), most large cities would be flooded. So, where do you live? I currently live in the center of the Florida peninsula, which would still be here after 6 feet of sea level rise... but loooooong gone by the time all the ice melts. Maybe I should start cleaning out stuff I won’t be needing in my old age, so that it’ll be easier to move north, once that becomes necessary.

By then, New Orleans would be a bay reaching almost as far north as the Missouri boot. The Netherlands would be entirely below sea level, but much of it is now. Hope they have plans for building new, much taller dykes. Australia will be a doughnut, with land surrounding an inland sea. The Amazon rainforest will become the Amazon Sea, and Buenos Aires in Argentina will mean a huge bay. Those are the easy things to notice on the map.

At one time, I found an interactive map showing what parts of the world would be underwater, and the results would change depending on how much you chose to raise the sea level. It didn’t seem too alarming, but I think it only allowed you to raise the sea level by 9 meters.

Alas, I neglected to bookmark that page. When I went looking for it to link to this blog, I found lots and lots of pages with ‘interactive global sea level rise maps’. That means more and more scientists (and others) have been looking at this scenario seriously, and taking the possible sea level rise much higher. Much more ice than that covering Greenland has been and is and will melt, so 9 meters could just be a drop in the bucket.

Water isn’t the only thing that will change. Next time, I’ll examine something else from my research about climate change.

https://www.dailykos.com/stories/2018/9/5/1792312/-Warm-ocean-water-has-penetrated-deep-into-the-Arctic-interior-portending-year-round-loss-of-sea-ice

http://www.softschools.com/facts/environmental_science/polar_ice_caps_facts/2894/

What is This World Coming to 2?

Okay, we were talking about the sea and what climate change is doing to it. My examples last time were in Europe and the US, in the northern temperate zones. Now I want to consider all that ice and water in the extreme north and south, around the poles.

If you’ve been paying attention, you might remember news of huge chunks of Antarctic ice breaking away. I’m talking chunks bigger than some states. Antarctica is receiving warmer weather than it’s seen in millennia, or maybe even millions of years. Some coasts that certain types of penguin have called ‘home’ for countless generations are becoming inhospitable for them. They already live at the bottom of the world, where are they supposed to go from there?

The Arctic Ocean is not doing any better. There is no land under all that ice at the north pole, just water. You might think, ‘That’s okay, because it takes a lot of energy to warm water up.’ Yes, it does. And yet, that water under that thick sheet of ice has warmed up.*

If you look at a map or globe, you’ll see a bunch of islands above Canada. During Europe’s Age of Exploration, several well-provisioned ships made attempts to find a ‘Northwest Passage’ during the summers, trying to find a way to get around the Americas to do trade with the Orient. I don’t remember hearing of any of those excursions ever making it through, nor of any making it home again. At that time, I understand, whatever open channels of water that could be found among all those islands were unreliable and tended to close up and freeze a ship in place, even in summer. The last few years, so much of that ice has melted during the summer, that some cruise lines have offered cruises from one coast to the other, via the Canadian passage.

Something has happened to the Beaufort Gyre. That is a 60-mile-diameter pool of cold freshwater and sea ice located north of Alaska. It used to spin clockwise for 5-7 years, then slow down and start spinning in the opposite direction. This change in direction was caused by periodic cyclones that moved from the Northern Atlantic Ocean into the Arctic Ocean. But the North Atlantic has been warming up even faster than other parts of the world, and has failed to get the Beaufort Gyre to change direction in a dozen years or more.

So it’s just been sitting there, spinning and getting larger. And although it contains ‘cold’ water, that’s a matter of relativity. This spinning water contains twice as much heat now as it did 30 years ago. But it’s not sitting on top, like you’d think it would. It extends so deep, it is creeping under the Arctic ice sheet, which I understand can be a mile or more thick. Once it starts melting that ice sheet from below, well, how long before that ice sheet starts to break apart into gigantic icebergs, like the Antarctic ice has already started doing?

And what happens when all that ice breaks up and melts? Right, it raises sea level, which we discussed last time.

I had never heard of the Beaufort Gyre until a couple days ago, but I’m not done with it. From what I’ve been reading, whether it continues its current spin or starts going the other way, somebody’s in for a nasty time. Maybe it will come up next time.

* https://www.dailykos.com/stories/2018/9/5/1792312/-Warm-ocean-water-has-penetrated-deep-into-the-Arctic-interior-portending-year-round-loss-of-sea-ice

What is This World Coming to?

I firmly believe in climate change. In my mind, it is here, and it’s going to get bad.

But I’m not here to debate that with anyone. So, for the purpose of this series of blog entries, let’s say I’m trying to figure out what could happen (climate-wise) in the next 50 years, and how it will effect the people who have to live through it. Well, try to live through it.

The sea level will rise. There has been and still is a lot of water on the Earth that is not located in the seas. It’s not a liquid, it’s solid in the form of snow and ice. Glaciers, sea ice, and so on. This has all been melting at an increasing pace, and probably will continue until snow and ice become rare items.

You can already see the sea level rising, if you look; Miami FL has streets that are underwater during high tides. Miami Beach, located on a barrier island that barely qualifies as dry land, is quietly raising its streets, particularly the ones that run along the edges of the island.

After Hurricane Katrina hit New Orleans, there was much talk of how badly the shoreline was being eroded. If I remember right, there is an oil refinery or some such that was built on the shore. Now it is pretty much an island, and the road leading to it may or may not be passable during high tides. Those tides even reach 5 or 10 miles inland, making it hard to get in or out of small towns that dot that road. The road, I understand, has been raised in a lot of places, making it even harder to navigate in those small towns.

Parts of Amsterdam in The Netherlands are 18 feet below sea level. Much of The Netherlands consists of land ‘reclaimed’ from the sea and thus below sea level. They did this by building dikes, dams and canals to control where the water could go. This will be an ever increasing chore, as the sea rises.

So I find myself wondering, what happens when the sea rise reaches that critical point, whatever it is? Will The Netherlands continue building their dikes taller, until they loom and cast an ominous shadow over the land they are intended to protect? Is that possible? Does it make more sense to raise the land they are living on? Is that possible?

At what point do people simply give in to nature and move to higher ground? Do those who are displaced get any assistance from their government, or do they have to abandon the home they’ve had for who knows how long, take what they can to some other place, and try to start over again? I suspect the latter, because the former would probably bankrupt any government.

Even if Earth’s population doesn’t grow beyond what it is now, it’s possible the concentration of that population will increase, because there could be less land for us to live on.

Well, with the next entry, we’ll continue with the water theme. Yes, there is more about water to think about.

Gone Fishing on Ganymede

In the past, fishing was a skill used to provide food for the table. Whether or not ancient man enjoyed the process, they needed to be good at it – or at hunting – in order to thrive. Today, fishing on a personal level has become a pleasurable activity for some. They don’t need to do it to put fish on the dinner table, but they find the experience rewarding. Some go so far as to try for ‘a big fish’ out in the middle of the ocean.

What do you suppose will happen when humans find their way to other planets?

Water has been found on our moon, Mars, Ceres, even Pluto, as well as various other places. On Ganymede, a moon of Jupiter, salty water is hidden under a thick (about 95 miles) crust of ice. There is probably more water on Ganymede than all of the Earth’s surface water combined. Scientists believe that ocean is 60 miles deep, about 10 times the deepest part of any Earth ocean.

I can envision future tours being organized to take die-hard fishers to Ganymede to drill a big hole in the exterior ice to facilitate fishing. I doubt if they’ll dangle a 100-mile-long fishing line into that hole – think how long it would take to reel it back in! So maybe their spacesuit for leaving the space boat would also be a diving suit, and they would ‘hunt’ for ‘fish’ with a spear gun.

Hmm. There’s problems with that vision, according to some of what I read. The Ganymede’s ocean is not only covered with ice, it also rests on ice, pressurized into a crystalized form. On other moons, the ocean bed is rock, which apparently keeps the water warmer, and provides various minerals as it is eroded by the salty ocean. The theory is that those warmer, rock-bedded oceans are far more likely to produce some kind of ‘life.’

Still, we keep getting surprised, the more we look around our neighborhood, don’t we? And science fiction writers like to take the science we know now and extrapolate possibilities we don’t – yet - have any proof for.

So, how about this? There’s a lot of different salts, besides table salt, which could be helping Ganymede’s ocean remain liquid. Nobody definitively stated the only salt in Ganymede’s ocean was NaCl (table salt), so these other salts could provide minerals for building ‘life’. I’m not sure the temperature of the ocean is that big a deal, but the salty ocean of Ganymede reacts to the magnetic field of Jupiter, and I’m thinking that reaction might produce some heat, although probably not much.

Sounds good to me. So good, I anticipate someone will make some money someday, selling signs that say, “Gone Fishing on Ganymede.”

http://www.space.com/28807-jupiter-moon-ganymede-salty-ocean.html

http://earthsky.org/space/underground-ocean-on-jupiters-largest-moon

http://www.planetary.org/blogs/emily-lakdawalla/2015/03121716-ganymede-ocean.html