Trudy Myers's Blog, page 19
September 24, 2021
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.
September 11, 2021
Jurassic Park Period Part 3
Flora
And now, let's move on to living things, such as plants. There's a lot of ground to cover, so to speak, so let's get to it. There is no evidence of a mass extinction of plants at the Triassic/Jurassic boundary, although some species did decline or even die out in some areas.
Conifers form a dominant component of Jurassic floras, when they underwent a major time of diversification. Most modern conifer groups appeared by the end of the Jurassic.
The oldest definitive record of the cypress family is from the Early Jurassic and were found in Patagonia (the southern area of South America). By the middle of the Jurassic, the cypress were abundant in warm temperate-tropical regions of the Northern Hemisphere.
Ancestors of the current pine family were widely distributed across Eurasia during the Jurassic.
The flora of the mid-latitudes of Eastern Asia were dominated during the Early Jurassic by a broad leafed conifer which shed its leaves seasonally, and which is not closely related to any living family of conifer. It extended northwards into polar latitudes of Siberia, and then contracted northward because of increasing aridity of the region.
Evidence of the yew family have been found in Sweden, England and China dating from the Middle Jurassic. They appear to be closely related to modern yew specimens.
Ginkgoales—which today has only one living specie, the Ginkgo biloba—were more diverse during the Jurassic, and were among the most important components of Eurasian Jurassic flora, adapted to a wide variety of climatic conditions.
Bennettitales are a group of seed plants that reached a peak diversity during the Triassic and Jurassic periods. Although they bear some resemblance to cycads, they are not believed to be closely related to them. All Jurassic Bennettitales grew as shrubs and small trees, and were adapted to grow in open habitat with poor soil. They also had flower-like reproductive structures that are thought to have been pollinated by insects.
Cycads reached their apex of diversity during the Jurassic and Cretaceous (which comes next) periods. Although this era is sometimes called the 'Age of Cycads', cycads are thought to have been a relatively minor component of Jurassic flora. Their foliage is often confused with that of Bennettitales and other plants. Cycads are thought to have been mostly confined to tropical and subtropical latitudes.
There are no widely accepted Jurassic records of true flowering plants, and fossil evidence suggests that the group diversified during the period following the Jurassic.
'Seed ferns' is a collective term to refer to fern-like plants that produce seeds but have uncertain affinities to living seed plant groups. One prominent group of seed ferns reached their zenith during the Jurassic and was widespread in the Northern Hemisphere, although records in the Southern Hemisphere are rare.
Another group of seed plants are known from the Late Triassic through the Jurassic to the Cretaceous. They are thought to have been tree- or shrub-like, and formed a conspicuous component of Northern Hemisphere Mesozoic temperate and warm-temperate floras. Another group of seed plants called the Pentoxylales, first appeared during the Jurassic, but appear to have been confined to Gondwana.
Many living families of fern were widespread during the Jurassic period. The Polypodiales ferns, which make up 80% of living fern diversity, have no record from the Jurassic and are thought to have diversified later, during the Cretaceous.
The oldest remains of modern horsetails first appear in the Early Jurassic. I could have sworn I heard mention of horsetails in earlier periods, but those must not have made it to modern times.
The Cyatheales, the group containing most modern tree ferns, appeared during the late Jurassic.
Quillworts that are virtually identical to modern species are known from the Jurassic onwards.
Various mosses have left fossil records from the Jurassic and are believed to be related to modern mosses. Several records of liverwort have also been found from the Middle Jurassic.
August 28, 2021
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.
August 21, 2021
Jurassic Park Period Part 1
Paleogeography
Everybody knows about dinosaurs, right? And thanks to the Jurassic Park series of movies, we all know the dinosaurs lived during the Jurassic Period. But what else is noteworthy about this geologic period? I'll try to uncover something other than various dinosaurs to study.
However, I am just as fascinated with dinosaurs as any little kid, so I'll spend some time studying some of our favorites while I'm at it.
The Jurassic Period started 201.3 million years ago and ended approximately 145 million years ago. There was, as seems so common with these geological periods, an extinction event at the dividing point between the Triassic and Jurassic Periods.
The Triassic/Jurassic extinction event seemed to be caused by the Central Atlantic Magmatic Province, which, as best I can figure out, means a lot of magma and lava was moving around in the areas currently known as northwestern Africa, southwestern Europe, southeastern North America and Northeastern South America.
The articles I read seemed to indicate that this was not just a matter of volcanic activity, that some of it could have been caused by the action of diverging plate tectonics. We are aware of the Atlantic rift, where two tectonic plates are moving away from each, allowing a large volume of magma to flow, but this is not considered a volcano. This magma movement began about 201 million years ago, and continued for about 600,000 years. It was the largest activity of this type known to man, covering roughly 11 million km2.
By the beginning of the Jurassic, the supercontinentPangaeahad begun rifting into two landmasses: Laurasia to the north and Gondwana to the south. The rifting between North America and Africa was the first to happen, in conjunction with the Central Atlantic Magmatic Province
By the beginning of the Jurassic, there was flooding in most parts of central and western Europe, transforming it into an archipelago of islands surrounded by shallow sea. Beginning in the Early Jurassic, the proto-Atlantic was expanded by the "Viking Corridor" (or Transcontinental Laurasian Seaway) which stretched between the Baltic Shield and Greenland, and was several hundred kilometers wide. All during the Jurassic, the North Atlantic Ocean remained relatively narrow, while the South Atlantic did not open until later.
At the beginning of the Jurassic, North and South America remained connected, but at some point, they rifted apart to form the Caribbean Seaway, which connected the north Atlantic Ocean with what is now called the Pacific Ocean, although it was much larger back then, taking up over half the globe and was called the Panthalass Ocean.
About 183 million year ago, another magmatic event started, the Karoo-Ferrar event, this one in South Africa and Antarctica. This triggered another extinction event by causing widespread oceanic anoxia, ocean acidification and elevated temperatures. I am uncertain if these types of conditions were responsible for the Triassic/Jurassic extinction event.
Madagascar and Antarctica rifted away from Africa in association with the eruption of the Karoo-Ferrar large igneous provinces, which opened the western Indian Ocean and began the fragmentation of Gondwana.
During the Middle to Late Jurassic, the Sundance Seaway, a shallow inland sea, covered much of northwest North America.
The sea level rose and fell many times during the Jurassic, peaking at one point as high as 140 meters (462 feet) above the present level.
Wow! So much happening! And that's just the geography! This makes me wonder what else was going on!
https://en.wikipedia.org/wiki/Jurassic
August 20, 2021
Giveaway Winners
The winners include Kerri of TN, Kelley of TX, Brittany of NY, Brenna of OH, Melissa of MO, Emma of KS, Tatiana of FL, Kathy of VA, Leslie of IL, and Shannon of ID. Congratulations to all of you. These books should be mailed tomorrow, or if something terrible goes wrong with my plans, Monday at the latest.
I really hope you all enjoy this book, and I want to thank everyone for signing up for my giveaway!
August 16, 2021
Hank's Widow
Wanda grew up in the suburbs of Chicago, but when her husband was killed in a winter traffic accident, she realized she couldn't afford their apartment on her own. So she moved to the tiny village of Belgrade, Nebraska, her husband's home town. Talk about culture shock! And it didn't help when she found 3 cousins of her dead husband, who all looked just like him!
August 10, 2021
Hank's Widow
When Wanda married Hank, she didn't know there were 3 more (cousins) back home that looked just like him. After Hank's death, she moved to his hometown, looking for a quiet place to write. It wasn't long before she met all 3 of those cousins. Will one of them manage to claim her heart?
August 7, 2021
The Joys of Learning
I research all sorts of science subjects in my spare time, not just to write a blog about what I've discovered, but because I enjoy learning new things. I love learning new tidbits of information that I can categorize and file in the proper drawer in my mind.
There's another aspect of my life where I find myself learning new things fairly regularly. It's the publishing portion of my life. Even though I belong to a number of groups where people talk about different aspects of publishing, every so often I find myself stuck, figuratively banging my head against a brick wall as I try to do something that looks so easy when others talk about it.
I think the first time this happened to me when I was just starting, and I was formatting short stories to be converted into e-books. It seemed like no matter how carefully I formatted the manuscript, I kept getting all sorts of error messages when I sent that first effort through the conversion software. That was where I learned the adage, "Read the guidelines, stupid." Yes, the owner of the software had a 100+ page book that he made available to users for free, and I had read the first 5 or 6 pages and figured that was enough.
It wasn't.
So I backed up a bit and read the entire book, taking special note of how to correct formatting problems. Turns out that formatting problems like I'd been having were possibly caused by file corruption created when the file has been through many, many forms of formatting. But there WAS a fix!
It sounded easy; take out all the formatting and start with a clean slate, format-wise. And getting rid of all that potentially-corrupted formatting was really easy to do, so I did it. Now for the down-side. Everything in my manuscript was now Times New Roman, 12 pt font, in body paragraphs. Now I had to go through the entire manuscript and put formatting back in: Chapter Headings and font size, centered; Title page things; back matter stuff... And once I had done that, I had to READ the manuscript and re-format anything that needed to be italicized, bolded, underlined. It was, all in all, a 4 or 5 day project, during which I got virtually nothing else done. But it works.
To this day, I cringe every time I decide I need to remove all the formatting and start over. But I do it, in order to get a good conversion to the various e-book formats. As my parents used to say, if it's worth doing, it's worth doing well.
Recently, I ran across a quick and simple method for inserting a Table of Contents. I took notes and tried it on my latest book. Something went wrong; every single paragraph of the manuscript was listed as a chapter in my Table of Contents. I tried 4 or 5 times, deleting the results after every attempt, before I gave up and did it the old way, which works for print books, but not so well for e-books.
So I backed up and re-read that style manual, looking for a better way to insert a ToC into my e-books. And I found the answer in those guidelines. Once again I had to delete all my evidently-corrupted formatting and set it up again. But 5 days later, when I followed the guidelines to insert a ToC, it worked! If I still had some flexibility in my shoulders, I would pat myself on the back! Who said an old dog can't learn new tricks?
Like I said earlier, I love learning new stuff.
Hank's Widow
She wanted a quiet place to pursue her writing career. He wanted her. Will her grief keep him from claiming her heart?
August 1, 2021
Hank's Widow Giveaway
In a way, Wanda has been spoiled during her marriage. Hank had a well-paying job, and she was able to quit her waitress job to concentrate on writing full time.
But when Hank was caught in a winter storm traffic accident and was suddenly gone, Wanda had to face the fact that she would need to find a job to support herself... her writing hadn't taken off that well in the last 5 years.
Then she finds a deed to a house in Hank's old hometown in Nebraska. He had owned the house free and clear. It seemed like a sign. So she moved to tiny Belgrade, where she could live rent free.
Things aren't as easy as that.
