Trudy Myers's Blog, page 24
August 21, 2020
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
August 14, 2020
Velociraptors
Velociraptors lived about 75 to 71 million years ago. There are 2 known species, both from Mongolia. The second species was only discovered in 2008.
They were depicted in the Jurassic Park movie as swift bipedal reptiles with a long tail and an enlarged sickle-shaped claw on each hindfoot, 6 1/2 feet tall and weighing about 180 pounds. Not so, say the scientists. They were bipedal reptiles, they were fast, and they had the fearsome claw. But they also had feathers, and were actually the size of a turkey. The raptors depicted in the movie series were based on a related genus, because the script said they had to look suitably fierce.
Instead of being 6.5 feet tall, velociraptors were as much as 6.75 feet long, snout to tail tip. Scientific artistic renditions show a very long, feathered tail. They were about 1 ft 7 inches high at the hip and weighs about 33 lbs. Although bipedal, their body and tail were roughly parallel to the ground. Their forefeet were also feathered, but were too short to serve as wings.
Their skulls grew up to 10 in long. The jaws were lined with 26-28 widely-spaced, serrated teeth on each side, more strongly serrated on the back edge than the front.
Their hands were large, with 3 curved claws. However, the structure of the wrist bones forced the hands to be held with palms facing inwards and not downwards.
On their feet, the first toe was a small dewclaw, and the 2nd held the ferocious claw spoken about earlier, which could get 2.5 inches long along its outer edge. Only their 3rd and 4th toes were used in walking or running. Although some beliere their 2nd toe claw was used for disemboweling prey, tests have proven it was most likely used for stabbing and holding, to keep their prey from escaping.
If we’re going to compare fiction to fact, then we must consider the depiction in the Jurassic Park movies of velociraptors hunting in packs. Although there are some indications of other species in the family hunting in packs, there is little to no indication in the fossils of velociraptors doing it.
Most of the known velociraptor fossils have been found in current desserts, under conditions that indicate the locale at the time of their death was also arid and covered in sand dunes, or possibly a little less arid.
Now, my first thought about incorporating velociraptors in a story involves a comedy-ish story where a town in the desert is suddenly overrun by predatory turkeys, which turn out to be—according to the local Wise Guy—descendants from velociraptors, long thought extinct these millions of years. Of course, once the raptors ate up all the local cats, dogs, and chickens, they would necessarily start picking on larger prey... large dogs, wolves, goats... children? Alas, I don’t do horror, which is where this thought is quickly leading me. Anybody out there have any other ideas?
https://en.wikipedia.org/wiki/Velociraptor
August 6, 2020
Ur...
Okay, not a lot of information on this subject. Only to be expected, I suppose, since Ur is the name given to the very first super continent, which came into being about 3.1 billion years ago. At that time, the only life on Earth was single-celled, and some of it knew how to photosynthesize. And it’s called a super continent, though it was probably smaller than modern Australia.
It qualifies as a super continent because it incorporated all or nearly all pieces of land then in existence. More recently, scientists have started calling Ur and other small ‘super’ continents by the term super-cratons. The best I can figure is that a craton is a piece of land considered too small to be a continent.
Other scientists have postulated the existence of another super-craton at about the same time, which they have called Vaalbara, but apparently, the ideas of these two early cratonic assemblages are incompatible.
About 1,300–1,071 million years ago, Ur joined the continents Nena and Atlantica to form the supercontinent Rodinia. In one proposal, Ur remained the nucleus of East Gondwana until that supercontinent broke up. But in other proposals, India and East Antarctica did not collide until Rodinia formed 1,071 Million years ago. However, during that time period, the Earth’s mantle was 200 degrees C hotter than today, making many characteristics of modern tectonics rare or non-existent. This would preclude Roger’s 3 billion years ago supercontinent of Ur.
The proposal for the super-craton Vaalbara places two cratons, Kaapvall of southern Africa and Pilbara of western Australia, next to each other based on stratigraphic similarities. In Roger’s configuration of Ur, these two cratons were placed far apart during Gondwana, which is contradicted by widespread collisional events between Australia and Africa.
Yet another possible supercraton, Zimgarn, was proposed by Smirnov in 2013. Unfortunately, I didn’t understand the paragraph dealing with it, so I’m mostly ignoring it. After all, I’m supposed to be studying Ur.
Geological similarities in parts of India (Singhbhum and Dharwar), western Australia (Kilbaran and Pilbara), and southern Africa (Kaapvall and Zimbabwe) indicate these area were close together in the Mid-Archaean Era. Ur was named for the german prefix meaning “original” by Rogers because in his proposal, it was the first continent. Other Archaean continental assemblages are considerably younger. In some reconstructions, the various pieces of Ur stayed near each other until the break-up of Gondwana.
So, was there really an Ur, as proposed by Rogers? Should it really be called Vaalbara or Zimgarn? Or something else entirely? I didn’t find any indication of where it was located, and given how long it supposedly existed, it could have drifted quite a ways from its original location, but still, I would have liked to see some of that type of information.
How many planets do you suppose are out there with only single-celled life and 1 large island? With such a small land mass, would it be worth it to colonize it?
https://en.wikipedia.org/wiki/Ur_(continent)
https://simple.wikipedia.org/wiki/Ur_(supercontinent)
July 23, 2020
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
July 9, 2020
Palm Trees by Another Name
The Arecaceae are perennial flowering plants. Their form can be as climbers, shrubs, tree-like and stemless plants. They are all commonly known as palms. Those having a tree-like form are called palm trees. There are 2,600 species of Arecaceae known, most of them restricted to tropical and subtropical climates. Most palms have large, compound, evergreen leaves (known as fronds) arranged at the top of an unbranched stem. Palms exhibit enormous diversity and inhabit nearly every type of habitat within their range, from rainforests to deserts.
Modern monocots appear in the fossil record around 80 million years ago, although specific species of Arecaceae appeared 94 million years ago, according to fossilized pollen. By 60 million years ago, many of the modern specialized palms became widespread and common, much more widespread than they are today.
The use of palms is as old or older than human civilization, starting with cultivating the date palm in the Middle East some 5,000 or more years ago. Date wood, pits for storing dates, and other remains of the date palm have been found in Mesopotamian sites. If not for the date palm, human expansion into the hot and barren parts of the “old” world would have been much more difficult. The date palm provided food which was easily stored and carried on long journeys. It provided shade and protection from the desert winds. It yielded such a variety of products that practically all parts of the palm had a useful purpose.
The economic importance of Arecaceae includes coconut products, oils, dates, palm syrup, ivory nuts, carnauba wax, rattan cane, raffia, and palm wood. There are a number of palms that can be used to make wine, at least one of which turns to vinegar within a day.
It kind of makes me want to go out and hug a palm tree, for without palms, who knows how long it might have taken humans to reach this point in their civilization? Which makes me wonder, would we have grown up any wiser if we had taken a slower path to get here? Or would that early difficulty of exploring the deserts have burned us into tighter powder kegs of anger that made our history even more bloody than what we experienced?
https://en.wikipedia.org/wiki/Arecaceae
July 3, 2020
Octopuses
The octopus is a soft-bodied mollusc with 8 limbs (also known as tentacles). About 300 species are recognized, and the order of Octopoda is grouped within the class Cephalopoda, along with squids, cuttlefish, and nautiloids. The octopus is bilaterally symmetric, with one side the mirror image of the other.
The 8 appendages of an octopus trail behind them as they swim, which they do by expelling a jet of water. With 8 arms to control, they have a complex nervous system. They also have excellent sight and are among the most intelligent and behaviorally diverse of all invertebrates.
With so many types of octopuses, they are found throughout the sea, from seashores to the abyssal depths. Most species grow quickly and don’t live very long. In most species, the male dies after mating, while the female watches over the fertilized eggs until they hatch, then she dies.
The octopus has many strategies to defend themselves, including the expulsion of ink, the use of camouflage and threat displays, the ability to jet quickly through the water and hide, and even deceit. Only one specie is known to be deadly to humans, although all octopuses are venomous.
The largest known octopus specie is the giant Pacific octopus. Adults usually have an arm span up to 14 ft (4.3 m) and weigh around 33 lb (15 kg). The largest specimen scientifically documented weighed 156.5 lb (71 kg), but much larger sizes have been claimed for the giant Pacific octopus, including one that weighed 600 lb (272 kg) with an arm span of 30 ft (9 m). A carcass of the seven-arm octopus was estimated to have a live mass of 165 lb (75 kg).
The smallest specie is octopus wolfi, which is about 1 in (2.5 cm) and weighs less than 0.035 oz (1 g).
The bulbous head of the octopus contains most of the vital organs. Lacking any bones at all, even large specimens of octopus can squeeze through a 1 inch gap, which can make them quite the escape artist!
I think we all know that the tentacles can bend in any direction at any location, and that the interior surface of the tentacles are covered in circular suckers. But I didn’t know that the octopus typically uses 2 tentacles to ‘walk’ along the sea floor, while the other 6 are used for foraging.
Octopuses have 3 hearts; a systemic heart that circulates blood around the body, and two branchial hearts that pump blood through each of the two gills. The systemic heart is inactive during swimming, so the animal tires easily and prefers to crawl. Their blood contains a copper-rich protein to transport oxygen. This makes the blood very viscous and bluish in color, but it transports oxygen more efficiently in cold water with limited oxygen availability than hemoglobin.
In several sets of mythology, octopuses appear as sea monsters, from the Kraken of Norway to the Gorgon of ancient Greece, and probably many more.
I saw a tv episode once on what evolution would do with today’s species in another million years, and one of the things suggested was that at least one specie of octopus would leave the sea to seek food in the forests on land. While this is an intriguing thought, I wonder if the octopus would have to develop some kind of support for its internal organs, to keep them from dragging along the ground, or a thick skin that could resist tearing and leaving those organs scattered behind it. Because it isn’t exactly dealing with the full force of gravity while it’s in the water, but it would have to once it came ashore.
https://en.wikipedia.org/wiki/Octopus
June 25, 2020
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
June 19, 2020
Dimetrodon
First, the dimetrodon was not a dinosaur. It went extinct some 40 million years before the first dinosaurs came into being, so it wasn’t even a contemporary of dinosaurs. However, it is often mistaken as a type of dinosaur, probably because life that long ago is all jumbled up in people’s minds.
Having said that, the dimetrodon lived around 295-272 million years ago. Its most prominent feature was a large neural spine sail on its back, formed by elongated spines extending from the vertebrae. Without the spine, it resembled a lizard, as it walked on 4 legs and had a tail. Its tall, curved skull had teeth of different sizes in the jaws. Most dimetrodon fossils have been found in southwestern United States, specifically from a deposit called the Red Beds of Texas and Oklahoma. However, there have been some fossils found in Germany. There are over a dozen species within the dimetrodon genus.
Although reptile-like in appearance, the dimetrodon is more closely related to mammals than to modern reptiles, although it is not a direct ancestor of mammals. It is assigned to the group ‘synapsids’, a group traditionally called ‘mammal-like reptiles’.
It was probably one of the apex predators of its time, feeding on fish, reptiles and amphibians. Smaller dimetrodon species may have had different roles in their ecological niche. The back sail may have been used to stabilize its spine or to heat and cool its body. Some recent studies argue that the sail would have been ineffective at removing heat, as large species have been discovered with small sails, and small species having large sails. This would appear to rule out heat regulation as its main purpose. It is proposed that the sail was most likely used in a courtship display, such as threatening rivals or showing off to potential mates.
Most species of dimetrodon range from 6 to 15 ft, and are estimated to have weighed between 60 to 550 lbs. The largest known species is about 13 ft. The smallest is 2 feet.
I remember seeing sail-backed giant lizards in a few movies. Always, they were supposed to be at least as tall as a man at their shoulder. Something that could easily eat a man without giving it much thought. This article only gave their length, not their height at their shoulder, so I can’t tell how much the movies may have ‘blown up’ their size. Considering they were most likely using a modern lizard with an fx sail glued to their back, the film crew probably got very close to make them look a threatening size.
How about you? Seen any good dimetrodon movies lately?
June 12, 2020
One Hump or Two?
A camel is an even-toed ungulate, which means it walks on 2 toes on each foot. They also have distinctive fatty deposits (humps) on the back. The Dromedary (94% of the world’s camel population) has 1 hump. The Bactrian camel (6% of the camel population) has 2 humps. The Wild Bactrian camel is a 3rd species and at less than 1% of the camel population, it is critically endangered. All of these camels are suited to a desert habitat. Except for the Wild Bactrian, camels have been domesticated for a long time, and have been a vital means of transport for passengers and cargo. As domesticated animals, they also provide food, such as milk and meat, and textiles via fiber and felt from hair.
Sometimes the word camel is used in a wider sense, to include not only the Old World camels but also New World camelids (llama, alpaca, quanaco and the vicuna). These new world animals are technically camelids, not camels.
Camels live an average of 40-50 years. An adult dromedary camel stands 6’1” at the shoulder and 7’1” at the hump, while Bactrian camels can be a foot taller. Camels can run in short bursts at 40 mph, and at a sustained speed of 25 mph. Dromedaries weight as much as 1,320 lbs, while Bactrians can get up to 2,200 lbs.
The earliest known camel is called Protylopus and lived in North America 40 - 50 million years ago. It was about the size of a rabbit and lived in the open woodlands of what is now South Dakota. By 35 million years ago, it was the size of a goat and had many more traits similar to camels and llamas. Other ancient forms of camels or camelids were the Stenomylius and the long-necked Aepycamelus.
The direct ancestor of modern camels (and perhaps of New World camelids as well) was Paracamelius, which existed 3 - 5 million years ago. It spread to South America via the Isthmus of Panama, and to the ‘Old World’ via the Bering Land Bridge. There have been surprising finds of fossil Paracamelius on Ellesmere Island (very much north of Canada and barely west of Greenland) which indicate the dromedary is descended from a larger, boreal browser whose hump may have evolved as an adaptation in a cold climate. This particular creature is estimated to have stood around 9 feet tall.
Which just goes to show that given enough time, evolution can completely adapt to an environment that otherwise would kill the original animal.
https://en.wikipedia.org/wiki/Camel
May 29, 2020
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
