Neanderthals’ Mysterious Extinction

Neanderthal DNA reveals 50,000-year-old viruses that could help explain their extinction. In a study of ancient Neanderthal DNA, researchers found traces of 3 viruses that cause colds, cold sores, genital warts, and cancer.

Ancient humans might have been responsible for spreading these bugs, but I don’t think we need to blame only homo erectus, for there were several types of ancient humans around at the same time as Neanderthals.

Most experts think the Neanderthal species went extinct from a variety of causes, including changing climate, low fertility rates and human interactions. As can be seen from illnesses that swept through American Natives after the arrival of European settlers, trying to recover from unfamiliar illnesses introduced by distant cousins wouldn’t have helped. Poor health can have a negative impact on survival.

Not only could these ancient viruses help explain the Neanderthals’ extinction, but they might help us better understand the modern versions that still infect humans today.

About 54,000 years ago, a group of Neanderthals lived in Chagyrskaya Cave in Southern Siberia. Researchers studied the DNA data of two people from the cave to look for 3 viruses: adenovirus, herpesvirus, and papillomamirus. Adenovirus can cause colds and flu, herpesviruses can cause cold sores or genital warts, and some cancers are linked to papillomavirus.

A 2021 study discovered adenovirus in 31,600-year-old human teeth from Siberia. This more-recent study is nearly 50,000 years old. Some experts estimate humans and Neanderthals interbred between 60,000 and 50,000 years ago. Besides DNA, they probably passed around diseases.

A 2016 study suggested that breeding with Neanderthals may have boosted humans’ immunity to previously unknown diseases. But the Neanderthals may have been less lucky. A cold does not have to be fatal to decrease hunting efficiency or other abilities. With an already small population, getting sick might have contributed to Neanderthals’ extinction roughly 40,000 years ago.

 

https://www.msn.com/en-us/health/other/scientists-discovered-50-000-year-old-viruses-in-neanderthal-dna-that-could-help-explain-their-mysterious-extinction/ar-BB1nKNuC?ocid=hpmsn&cvid=f10bd090b2834e28ca31725fb862078f&ei=41

 

Jurassic Park Period Part 5

Fauna - Fish

I don't have as much information on the fish of the Jurassic as I had on the reptiles. So this blog might not be as long. But we'll see.

Conodonts - This is a class of jawless fish that had hard tooth-like elements. They were mentioned in the article I consulted only because they died out during the Jurassic, although not all over the globe at the same time. They had over 300 million years of evolutionary history, but only a handful of species made it into the Jurassic, and those went extinct early in the period. So they wouldn't have been plentiful in the oceans, but there might have been some, depending on what time during the Jurassic period a person was looking.

Sarcopterygii - This is a fancy name for lobe-finned fish, a class of fish whose fins are attached to their bodies by a single bone. This includes several genera of lungfish, which lived in freshwater environments in both hemispheres. Some of those lungfish are fairly closely related to lungfish now living in South America and Africa, rather than those living in Queensland. And there were some living in Asia that are not closely related to any group of living lungfish. Another group of this type of fish were the Mawsoniids, which are completely extinct now, but which lived in the oceans or fresh or brackish water.

Bony fish (Actinopterygii) were major components of freshwater and marine ecosystems. Among these were the Amiiform fish, which are represented today only by the bowfin, an elongated, eel-like creature with sharp, pointy teeth that live in slow-moving fresh water. During the Jurassic, the Amiiformes became fairly global. The pycnodontiforms were small to middle-sized fish with laterally-compressed body and an almost circular outline. They lived mostly in shallow-water sea. They had round and flattened teeth, well adapted to crush food items. Some species lived in rivers and possibly fed on molluscs and crustaceans. Although they had a large variety of representatives during the Jurassic, they are all extinct now. Teleosts, which currently make up over 99% of living Actinopterygii, appeared during the Triassic and underwent a major diversification during the Late Jurassic. The Pachycormiformes are a group of fish closely allied to teleosts. They first appeared in the Early Jurassic, and included both tuna-like predatory and filter-feeding forms. This included the largest bony fish known to have existed, with an estimated maximum length over 15 metres (45 feet).

Chondrichthyes - are fish whose skeletons are mostly made of cartilage, rather than bone. During the Early Jurassic, Hubodonts, which appear to have been primitive forms of sharks were common in both marine and freshwater settings. However, by the Late Jurassic, hybodonts were minor components of most marine communities, having been largely replaced by neoselachians, which contains all living sharks and rays. Hybodonts remained common in freshwater and restricted marine environments. Relatives of the bullhead shark, carpetsharks, and mackerel sharks all made their appearance during the Jurassic. There were also other examples of extinct and relatives of now-living sharks mentioned, so I would suppose that shark-like creatures were a regular feature in the oceans.

So there were plenty of fish in the seas.

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

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

Triassic Period Part 2

 Now let's take a look at the inhabitants of the Triassic Period.

Three categories of organisms can be distinguished in the Triassic record: survivors from the Permian–Triassic extinction event, new groups which flourished briefly, and other new groups which went on to dominate the Mesozoic Era.

To go back to the beginning, after the extinction event just before the Triassic Period began, the Earth's biosphere was impoverished. It was well into the middle of the Triassic before life recovered its former diversity. Therapsids (including what would become mammals) and archosaurs (including crocodilian reptiles) were the chief terrestrial vertebrates of this period. A specialized subgroup of archosaurs, called dinosaurs, first appeared late in the Triassic, but did not become dominant until the succeeding Jurassic Period.

The first true mammals also evolved during this period, as well as the first flying vertebrates, the pterosaurs, who were a specialized subgroup of archosaurs.

In marine environments, new types of corals appeared in the Early Triassic, forming small patches of reefs of modest extent compared to the great reef systems of modern times. The shelled ammonites (whose shell resembled that of the modern nautilus, but is not an ancestor) recovered, diversifying from a single line that survived the Permian-Triassic extinction.

The fish fauna was remarkably uniform, with many families and genera exhibiting a global distribution in the wake of the mass extinction event. There were also many types of marine reptiles. The first of the lizard-like animals appeared in the Early Triassic seas and soon diversified, and some developed to huge size during the Late Triassic.

On land, the surviving plants included ginkos, ferns, and horsetails, among others. Seed plants came to dominate the terrestrial flora. In the northern hemisphere, conifers and ferns flourished. A seed fern genus would dominate Gondwana throughout the period.

Many groups of terrestrial fauna appeared in the Triassic period or achieved a new level of evolutionary success during it. They include lungfish, Temnospondyls (early amphibians that had mostly been replaced by reptiles, they made a come-back in this period), Rhynchosaurs (the primary large herbivores in many Triassic ecosystems), Phytosaurs (looked like crocodiles, but unrelated), Aetosaurs (heavily armored and mostly herbivorous), Rauisuchians (the keystone predators of most Triassic terrestrial ecosystems), Theropods (dinosaurs but not the large kind that would come later; most were 1-2 meters long), and Cynodonts (a large group that includes true mammals, complete with hair and a large brain).

Some amphibians were among those groups that survived the Permian-Triassic extinction event. The first ancestors of frogs are known from the Early Triassic, but did not become common until the Jurassic (which comes next).

Among reptiles, the earliest turtles appeared during the Late Triassic Period.

During the Triassic, archosaurs displaced therapsids as the dominant amniotes. This may have contributed to the evolution of mammals by forcing the surviving therapsids and their mammalia-form successors to live as small, mainly nocturnal insectivores. Nocturnal life may have forced the mammaliaforms to develop fur and a higher metabolic rate.

Though the end-Triassic extinction event was not equally devastating in all terrestrial ecosystems, several important clades of large reptiles disappeared, as did most of the amphibians, groups of small reptiles, and others (except for the proto-mammals). Some of the early, primitive dinosaurs also became extinct, but more adaptive ones survived into the Jurassic. Surviving plants that went on to dominate the Mesozoic Era included modern conifers.

The cause of the Late Triassic extinction in uncertain. It was accompanied by huge volcanic eruptions that occurred as the supercontinent Pangaea began to break apart about 202 to 191 million years ago, forming one of the largest known inland volcanic events since the planet had first cooled and stabilized. Another possible but less likely cause for the extinction event might be global cooling.

 

 

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

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

Silurian Period

After the Ordovician Period came the Silurian Period, lasting 24.6 million years, from 443.8 million years ago to 419.8 million years ago. It began approximately the same time as the major series of extinction events mentioned at the end of the Ordovician Period, when a large number of marine fauna were wiped out.

The Silurian saw wide-spread diversification of jawed fish as well as bony fish. Multi-cellular life also appeared on land as small plants similar to liverworts, hornworts, and mosses, which grew besides lakes, streams and coastlines. Invertebrate animals with an exoskeleton also found land during this time period. This includes insects, spiders and crustaceans. However, terrestrial life would not greatly diversify until later.

With the supercontinent Gondwana still covering much of the southern hemisphere, a large ocean occupied most of the northern half of the globe. High sea levels and relatively flat land (there were few significant mountain belts) produced a number of island chains, meaning there was a rich diversity of environmental settings.

What was left of Gondwana remained intact and continued to drift south, but there is evidence that the icecaps were less extensive than those of the late-Ordovician time period. The smaller continents of Avalonia, Baltica, and Laurentia drift together near the equator, starting the formation of a second supercontinent known as Euramerica.

When proto-Europe (Baltica) collided with proto-North America (Laurentia), the collision folded coastal areas from modern New York State through Europe and Greenland to Norway. At the end of the Silurian Period, sea levels dropped again, and the new mountain ranges were rapidly eroded.

The Silurian period enjoyed relatively stable and warm temperatures, in contrast with the extreme glaciations of the period before it, and the extreme heat that would follow it. Sea levels rose during the first half of this period, and fell during the second half.

Climate was warm because high CO₂ levels and warm shallow seas produced a greenhouse phase. Glaciers at the South Pole nearly disappeared entirely. There is strong evidence of a climate dominated by violent storms generated by warm sea surfaces.

The Silurian was the first period to have megafossils in the form of moss-like miniature forests along lakes and streams. The first fossil records of vascular plants (land plants with tissues that carry water and food) appeared in the second half of the Silurian period.

Fish reached considerable diversity. A diverse fauna of sea scorpions (some of them several meters in length) prowled the shallow Silurian seas of North America. Leeches made their appearance.

About the middle of the Silurian, the earliest-known animals fully adapted to terrestrial conditions appeared, including a millipede. There is also some evidence of predatory spiders and millipedes and centipedes. Predatory invertebrates indicate that simple food webs were in place that included prey animals. These may have included those who grazed on micro-organisms.

Yes, we are getting closer and closer modern Earth. That is what happens when you start at the beginning and work your way towards today. I'm still not seeing any fauna that would be worth hunting. Although a millipede several meters in length might have enough meat to make a stew. Is the ground fertile enough to grow carrots and potatoes to put in that stew? And just how bad did those storms get? Maybe I'll keep going before I try to colonize.

 

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

Rhynchosaurs

Imagine a reptilian pig with a hammerhead, no visible ears, and a parrot-like beak, and you'll have a pretty good mental picture of a rhynchosaur.

Rhynchosaurs were herbivores that in some fossil localities account for 40 to 60% of the specimens found, making them the most abundant plant eaters on land. They were reptiles with stocky bodies and a powerful beak.

Early forms were small, less than a meter long, and typically lizard-like in build. They had narrow, wedge-shaped skulls with a few small, blunt teeth for eating plants.

Later versions grew up to two meters in length. The skull in these later forms were short, broad and triangular, becoming much wider than long, giving them a somewhat hammer-head appearance, although the eyes were set close together, near the top of the beak. The broad skull accommodated powerful jaw muscles that enabled the rhynchosaurs to cut up tough plant material. The teeth were modified into broad tooth plates, and the lower jaw fit into a groove on the upper jaw, enabling the ‘cutting’ of plant fibers.

The hind feet were equipped with massive claws, presumably for digging up roots and tubers, although digging claws are usually found on the front feet. Like many animals of their time, they spread all across Pangea, and thus across the world.

And that seems to about all there is to say about the rhynchosaurs. They lived during the Triassic era (251 to 199 million years ago), dying out just before herbivore dinosaurs appeared.

I think I would have found rhynchosaurs terrifying, particularly the larger ones, even though they were basically reptilian cows or deer. Let’s face it, the larger ones were as long as a man is tall, and who’s to say they wouldn’t try munching on this new plant called human that invaded their space, even if it didn’t sit still like other plants?

What do you think? If you had a time machine, would you venture back to visit them up close and personal?

 

https://ucmp.berkeley.edu/taxa/verts/archosaurs/rhynchosauria.php

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

Nimravs

I couldn’t help but look up Nimravidae; the name reminded me of ‘nimrods’, which of course have nothing to do with Nimravidae. Naturally, I didn’t know that until I looked it up.

The Nimravidae were a cat-like creature whose fossils have been found in North America and Eurasia. They are sometimes called ‘false saber-toothed cats’. They existed from about 40.4 million years ago to 7.2 million years ago, spanning some 33.2 million years.

It is thought that the ancestors of nimravids and cats diverged from a common ancestor about 50 million years ago. Nimravid diversity appears to have peaked about 28 million years ago before the family began a slow descent into extinction. This diversity was apparent in the size and shape of their teeth, as well as the size of the body. Some nimravidae were the size of modern lions, and they had various other smaller sizes down to the size of a small bobcat. Their legs and tails were proportionally shorter than those of true cats.

When nimravid first appeared, the global climate was warm and wet, but it trended cooler and drier shortly after that. This meant the lush forests were transforming to scrub and open woodland, where the nimravids flourished. North America and Asia were connected at the time, and they inhabited both. Europe was more of a cluster of islands rather than a continent at the time, but there must have been some land bridges, for the nimravids also found their way there.

Still later, the woodlands were replaced by savanna in North America and Asia, and the nimravids in those areas died out. Portions of humid forests continued in Europe for a time, but when those died out in the late Miocene, so did the rest of the nimravids.

One has to wonder if the saber-tooth tiger that Fred Flintstone put out of the house every evening was really a saber-tooth tiger or actually a nimravidae.

On second thought, there may be a tenuous connection between ‘nimrod’ and ‘nimravidae’. The dictionary tells me that ‘nimrod’ refers to a person who is good at hunting. As a carnivorous species, the nimravidae had to be good at hunting. Now I wonder if that influenced whoever named this family of creatures. Or what exactly does ‘nimravidae’ mean in whatever language they used to construct this name?

  

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

https://www.britannica.com/animal/Nimravidae

Jonah in a Basilosaurus

Okay, probably not what happened, because we are talking about an extinct species here. Basilosaurus means “king lizard” and it is a genus of large, predatory, prehistoric whale, living from approximately 41.3 to 33.9 million years ago. It was first described in 1834, based on fossils found along the Gulf Coast of the US, along with a few fossils in the eastern US. It was thought to be a giant reptile, hence the -saurus ending to the name. They were later discovered to be an early marine mammal, but it was too late to change the name.

 Likewise, the genus Basilosaurus was something of a wastebasket for odds and ends of fossils that nobody thought belonged anywhere else. But most of those have been removed and placed in more correct classifications, leaving 2 species in this genus.

 Unlike modern whales, who swallow their food whole, the Basilosaurus had various types of teeth, such as canines and molars, so it probably chewed it food. It was the top predator of its environment, preying on sharks, large fish and other marine mammals, such as another early whale, the Dorudon, which seems to have been their predominant food source.

 At a size of 49-66 ft (15-20 m), Basilosaurus  is one of the largest known animals existing from 66 million to 15 million years ago. Basilosaurus Isis is  slightly smaller than Basilosaurus Cetoides by about 7 feet.

 Basilosaurus appear to be closely related to even-toed ungulates, such as giraffes and buffalo. Does that mean it was a land animal that reverted to living in the sea? I don’t know.

 It is not believed that Basilosaurus could produce high-frequency sound and echolocation, which some modern whales can do.

 Studies of a complete skeleton fossil as well as overlapping skeletal reconstruction indicate Basilosaurua had about 70 vertabrae. They were shaped much like eels, and probably moved much like eels as well, mostly at or near the ocean’s surface, as they do not appear to have had a method for diving.

 So, if a person by the name of Jonah had been at sea during the time period, I suppose he could have been eaten by a Basilosaurus. But living through being eaten would have been problematic, since the Basilosaurus would have chewed before swallowing

 Since these were marine mammals, I suppose their ancestors were land mammals that - for whatever reason - decided to return to the water. And other branches of the family went on to become giraffes and buffalo, among others? What a family tree!

 

 

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

Giraffe Evolution

I’ve known for some time that giraffes and okapi are related. But in looking up giraffe evolution, I’ve discovered that giraffes are also (distantly) related to pronghorns, deer, musk deer, cattle, goats, sheep, wildebeests, and antelope. What a wide-ranging family! However, the opaki are their closest relative, so close that a 7-million year old fossil had a neck that was a blending of a giraffe neck and an opaki neck.

Giraffe and opaki ancestors once roamed all of Eurasia, but in modern times, they are only found in Africa. Giraffes live in the savanna grasslands, while okapi live in the rain forest.

One possible early ancestor of giraffes is the Canthumeryx, which lived in Libya. No one is sure when it lived; guesses range from 25 million years ago to 14.3 million years ago. It was a medium-sized animal, slender and antelope-like.

About 15 million years ago, Giraffokeryx appeared in the Indian subcontinent. It may have resembled an okapi or a small giraffe. It showed some definite lengthening of the neck.

The Sivatherium ranged throughout Africa and to the Indian subcontinent about 1 million years ago, and may have gone extinct as recently at 8,000 years ago, as ancient rock paintings greatly resemble them. The picture of a reconstruction of one show a pair of horns that look rather like the horns of a Texas longhorn, but only about a foot long each. The neck wasn’t as long as a modern giraffe, and the spots are depicted as being not quite so regular. It stood 7.2 feet tall at the shoulder, with a total height of 9.8 ft and a body weight of up to half a ton. Its shoulders were very strong to support the neck muscles required to life the heavy skull.

There was another giraffe-type animal that ranged from India to Turkey called the Bramatherium, which was closely related to the Sivatherium.

The Shansitherium was a superficially moose- or antelope-like giraffe from the Shanxi province in China. They were closely related to the Samotherium, which was rather like a half-way point between a giraffe and an opaki, as far as size goes.

Giraffes have horns! They are actually called ossicones, being made of bone and covered in furry skin. Some of their ancestors had 2, like modern giraffes, and some had 4. Sometimes they stuck up, or stuck up and curved back, or maybe they stuck out vertically. The Sivatherium horns as I described looked like small longhorns, did not look to be covered in furry skin, but they also had a pair of ossicones above their eyes.

So, if I ever want to make up a giraffe-like alien creature, I now know there is plenty of leeway for using my imagination!

https://evolution-institute.org/how-giraffes-evolved-such-a-large-neck/

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

Extinction Event 1

We all know the dinosaurs went extinct. Okay, most of them. But that was not the first ‘Great Extinction Event that Earth has suffered. Since I’m really only aware of that one and its possible cause, I decided to investigate the first one, just to see what I could find. Apparently, it was caused by oxygen!

I know, right? Something we think is a good thing, yet it caused a massive die-off! How could this be? Let’s take a look.

First, let’s be sure we understand what an extinction event is; it is a widespread and rapid decrease in the biodiversity on Earth. Estimates of how many extinction events we’ve already had range from 5 to as many as 20.

Most life on Earth is microbial and thus difficult to measure. Therefore recorded extinction events are those that affected the easily observed, biologically-complex component of life on Earth. Normally, extinction of various lifeforms occur at an uneven rate. An Extinction Event is when a lot of different lifeforms go extinct at pretty much the same time.

The Oxygenation Crisis occurred around 2.45 billion years ago, but technically, as I studied it further, it is not considered one of The Great Extinction Events. Maybe because it’s hard to find fossils from that long ago, so they can’t be sure what died off and in what numbers, but it was big enough that the fossils they have found indicate something happened.

From what I understand, Earth’s atmosphere at the time had next to no free oxygen in it. But then photosynthesizing cyanobacteria (which some call blue-green algae) evolved in the shallow sea that covered most of Earth. The cyanobacteria did what it does, and in the process, released free oxygen into the water. Eventually, the water couldn’t hold any more of it and released free oxygen into the air. All this free oxygen (which was a mere pittance compared to what we currently have in our atmosphere) played havoc with the metabolism of most of the living organisms at the time and a great deal of them died.

And the cyanobacteria continued putting out more oxygen.

Which opened the gates for more complex biolife forms.

So, extinction events are not always a bad thing... if you aren’t a species that is going extinct. But they do tend to create ‘bottle-necks’ of survival, which are followed by much evolving and diversification to fill all the empty niches that result.

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