Caffeine said:
quote:
Pterosaurs did stuff in common with birds; in the sense that they were also flying animals; and in that they appear to be the closest known relatives of dinosaurs (which birds, of course, are).
They had more in common with birds than you make it sound, and especially a lot more in common with archaeopteryx.
See this:
quote:
Pterosaur - Wikipediahttps://en.wikipedia.org/wiki/Pterosaur
Pterosaur bones were hollow and air-filled, like the bones of birds. They had a keeled breastbone that was developed for the attachment of flight muscles and an enlarged brain that shows specialised features associated with flight.
see this:
quote:
Pterosaurs, the earliest flying vertebrates, first appeared in the fossil record around 228 million years ago. Almost all have been found to have long tails and short skulls, necks and hands. According to the study, some time during the Jurassic period, pterosaurs underwent a “body plan reorganization” that resulted in the origin of the more advanced pterodactyloids, which appeared 60 million years later.But for decades an incomplete fossil record kept the pterodactyloid’s origins a mystery, forming a wide gap between giant flying reptile and its closest pterosaur relative. Without that link, researchers’ understanding of the pterodactyloid was stunted, leaving many questions about the creature’s and evolution unanswered.
Then, in 2001, an international team — that included Andres, George Washington University biology professor James Clark, and Xu Xing of the Chinese Academy of Sciences — found pterodactyloid fossil remains in the mud pits of northwest China.
https://www.pbs.org/...evolution-gap-ancient-flying-reptiles
And they had a common ancestor that predated the dinosaurs.
quote:
Whenever a story about pterosaurs makes it into mainstream news outlets, it is almost inevitable the flying archosaurs are going to be mistakenly called “dinosaurs” by at least one source.
....
It might be easy to brush off my complaint as a case of paleo-pedantry, but word choice matters. “Dinosaur” is a word for a specific group of creatures united by shared characteristics and which had their own evolutionary history—it is not a catch-all term for anything reptilian and prehistoric. Calling a pterosaur a dinosaur is an error of the same order of magnitude as saying that our species is a marsupial, but to understand why we need to flesh out the evolutionary relationships of these animals
....
Let’s start from the bottom and work our way up. The Archosauria is a diverse group of reptiles which contains two major subsections: crocodiles and their close relatives (collectively called crurotarsans or pseudosuchians) are on one side of the split, and dinosaurs, pterosaurs, and their closest relatives (called avemetatarsalians) on the other. For our purposes here, we’re concerned with the second group.
Looking at the Avemetatarsalia (see the diagram above), a major split is apparent at the base of this group. On the one side are the dinosaurs and their closest relatives, and on the other are pterosaurs and animals more closely related to them than dinosaurs. Both pterosaurs and dinosaurs are distinct groups that shared a common ancestor, and so to call a pterosaur a dinosaur is to ignore this major divergence in the evolution of both groups. A pterosaur is no more a dinosaur than a goldfish is a shark.
https://www.smithsonianmag.com/...is-not-a-dinosaur-87082921
Birds have a 4 chambered heart like Crocodiles, which come from a line that predates dinosaurs.
quote:
Crocodilia - Wikipediahttps://en.wikipedia.org/wiki/Crocodilia
It has a four-chambered heart and two ventricles, an unusual trait among extant reptiles, and both a left and right aorta which are connected by a hole called the Foramen of Panizza. Like birds and mammals, crocodilians have heart valves that direct blood flow in a single direction through the heart chambers.
quote:
Why do crocodiles have a four-chambered heart? - Quora
https://www.quora.com/...codiles-have-a-four-chambered-heart
Reptiles tend to have a three chambered heart i.e,they have a common ventricle because of incompletely developed septum.But crocodile inspire of being a reptile has a completely developed septum due to which the ventricle is divided into right and left …
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Crocodile hearts | Science News for Students
https://www.sciencenewsforstudents.org/...e/crocodile-hearts
A crocodile's heart may help it digest large, bony meals. U.S. Fish & Wildlife Service Like mammal and bird hearts, a crocodile's heart is a muscle that pumps blood.
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How many chambers do the crocodile have? - Quora
https://www.quora.com/...many-chambers-do-the-crocodile-have
Crocodiles have four chambered heart same as birds and mammals involving two ventricles and two auricles. Its an exception in the reptile family as the reptiles have ...
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Did crocodiles always have 4 part heart, or did they …
https://plantsm14.imascientist.org.uk/...3/19/did-crocodiles...
Did crocodiles always have 4 part heart, ... don’t have a four chambered heart. ... it means that when the crocodile is underwater it’s heart rate can slow ...
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How many chambers does a crocodile's heart have?? | …
https://answers.yahoo.com/question/index?qid=200711242344...
Nov 24, 2007 · Best Answer: Crocodiles have structurally speaking fully separated four-chambered hearts, but have strangely enough several features that allow the mixing of oxygenated and deoxygenated blood, so that the crocodile circulatory system can function as though it had a three-chambered heart.
Status: Resolved
Answers: 5
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iucncsg.org - The Crocodilian Body
www.iucncsg.org/pages/The-Crocodilian-Body.html
Crocodilians, like mammals and birds, have a four-chambered heart (two atria and two separate ventricles). In the three-chambered reptile heart, blood destined for the lungs (deoxygenated blood) can mix in the partly divided ventricle with blood destined to go out to the body (oxygenated blood from the lungs).
How much is known about this common ancestor that predates the dinosaur?
How much has been found?
How much can be said?
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What was the common ancestor of all dinosaurs?Laura Cooper, Biologist-in-training, autistic, feminist.
Answered Dec 26, 2014
All dinosaurs are, along with crocodiles, pterosaurs, avian dinosaurs (aka birds) and others archosaurs. They are also members of the group Dinosauriformes, which includes dinosaurs and their closest possible non-dinosaur relatives. The non-dinosaur Dinosauriformes became extinct in the Triassic and only the true Dinosaurs remained. Therefore, the last common ancestor of all dinosaurs would have a Dinosauriformes from the Mid Triassic. It is likely that this creature would have looked a little like this:
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This is the 235 million year old Lagosuchus, and it together with Marasuchus is believed to be close to the transitional form between cold blooded reptiles and warm blooded true dinosaurs.
Dinosaur Institute Origin of Dinosaurs | Natural History Museum of Los Angeles
We can rarely say for sure that we have found the last common ancestor of anything, as it is so hard to recognize a last common ancestor and it is unlikely that we have found the fossil of the last member of a species, before the species evolved into another one.(it can be estimated using molecular clocks, but that doesn't tell you the species of the organism), but an organism similar to Lagosuchus is probably something like that last common ancestor.
https://www.quora.com/...he-common-ancestor-of-all-dinosaurs
quote:
Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic periodhttps://en.wikipedia.org/wiki/Dinosauriformes
Not a broad window.
We are talking around 245 to 235 million years.
Much is missing, and links galore from before and after ( not to mention endless horizontal links like a chin linked fence)
Caffeine writes:
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Pterosaurs and dinosaurs both appear before 200 million years ago, but I'm not sure why you consider this significant. Both groups first appear during the Triassic (which lasted from about 250-200 million years). You seem to be assuming that 'amphibian' means an animal which lives in water; but even today we have amphibians that live in deserts. At a time when the only terrestrial vertebrates were 'amphibians' (which in this sense just means non-amniote - ie; not part of the group including reptiles, birds and mammals), there would be less competition in fully terrestrial ecosystems. Whether or not something is a 'reptile' does not tell us whether it lived in dry conditions.
But in the Permian, there were lots of uncontroversial amniotes, and some of them lived in deserts.
Look at the Carboniferous period, which had lots of acidic forests, in which bird-like bones would dissolve.
quote:
Tetrapods[edit]Carboniferous amphibians were diverse and common by the middle of the period, more so than they are today; some were as long as 6 meters, and those fully terrestrial as adults had scaly skin.[29] They included a number of basal tetrapod groups classified in early books under the Labyrinthodontia. These had long bodies, a head covered with bony plates and generally weak or undeveloped limbs. The largest were over 2 meters long. They were accompanied by an assemblage of smaller amphibians included under the Lepospondyli, often only about 15 cm (6 in) long. Some Carboniferous amphibians were aquatic and lived in rivers (Loxomma, Eogyrinus, Proterogyrinus); others may have been semi-aquatic (Ophiderpeton, Amphibamus, Hyloplesion) or terrestrial (Dendrerpeton, Tuditanus, Anthracosaurus).
The Carboniferous Rainforest Collapse slowed the evolution of amphibians who could not survive as well in the cooler, drier conditions. Reptiles, however, prospered due to specific key adaptations.[11] One of the greatest evolutionary innovations of the Carboniferous was the amniote egg, which allowed the laying of eggs in a dry environment, allowing for the further exploitation of the land by certain tetrapods. These included the earliest sauropsid reptiles (Hylonomus), and the earliest known synapsid (Archaeothyris). These small lizard-like animals quickly gave rise to many descendants, reptiles, birds, and mammals.
Reptiles underwent a major evolutionary radiation in response to the drier climate that preceded the rainforest collapse.[11][30] By the end of the Carboniferous period, amniotes had already diversified into a number of groups, including protorothyridids, captorhinids, araeoscelids, and several families of pelycosaurs.
https://en.wikipedia.org/wiki/Carboniferous
The Archaeothyris type (from 306 million years ago) is a point of interest, and birds might have evolved from a common ancestor, that dated much earlier.
Crocodile teeth tell a story.
http://abcnews.go.com/Technology/DyeHard/story?id=909287&...
brain clues:
http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0185(19991015)257:5%3C162::AID-AR5%3E3.0.CO;2-W/full
Put into bing:
bird lungs parallels ancestors fossil record dinosaurs crocodiles
quote:
Origin of birds - Wikipedia
https://en.wikipedia.org/wiki/Origin_of_birds
The origin of birds ... He was therefore forced to rule out dinosaurs as bird ancestors ... The successful extraction of ancient DNA from dinosaur fossils ...
Research history ·
Phylogeny ·
Features linking ... ·
Debates ·
Footnotes
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Evolution of reptiles - Wikipedia
https://en.wikipedia.org/wiki/Evolution_of_reptiles
Late in the period, the diapsid reptiles split into two main lineages, the archosaurs (ancestors of crocodiles and dinosaurs) and the lepidosaurs (predecessors of modern tuataras, lizards, and snakes).
First reptiles ·
Rise of Dinosaurs ·
The four orders of ...
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Pulmonary anatomy in the Nile crocodile and the ... - PeerJ
https://peerj.com/articles/60
... and caudally to cranially in the dorsobronchi in the lungs of Nile crocodiles. ... The lungs of birds have long been known to ... in the fossil record with an ...
also put into engines:
archaeopteryx sac tubular lung
Archaeopteryx has a sac lung like the dinosaurs commonly said to be in their direct line ( sauropod therapod).
PaulK said:
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The idea is that birds evolved from small theropod dinosaurs.
This was a criticism of my comment which indicated that Dinosaurs weren't ancestors
I said:
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The idea is that all birds came from big bulky dinosaurs and it might be true
Here is an expert:
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FROM THE FEBRUARY 2003 ISSUE Ornithologist and Evolutionary Biologist Alan Feduccia—Plucking Apart the Dino-Birds
By Kathy A. Svitil|Saturday, February 01, 2003
Many of today's paleontologists say birds are dinosaurs—specifically, the surviving members of a group called theropods. But is it true? Alan Feduccia, an ornithologist and evolutionary biologist at the University of North Carolina at Chapel Hill, doesn't think so. He and a handful of other skeptics argue that birds evolved from an early dinosaur ancestor, making them only slightly closer relatives of T. rex than lizards are. Feduccia shared his views with Discover associate editor Kathy A. Svitil.
Why don't you think birds are descended from dinosaurs?
First, the time line is all wrong. These alleged dinosaurian ancestors of birds occur 25 million to 80 million years after Archaeopteryx, the earliest known bird. Second, by the time you get to dinosaurs, you are dealing with fairly large, earthbound creatures, which means they would have had to evolve flight from the ground up, rather than from the trees down. Evolving flight from the ground up is biophysically implausible.
Third, many of the features of birds and dinosaurs—the hands and teeth for example—don't match. The theropod dinosaur hand consists of the thumb and the next two fingers. The bird hand is made up of the middle three fingers. You can't just flip a switch to go from one type of hand to the other. Of course, it doesn't matter what line of evidence you come up with, you are automatically wrong if it is anything contrary to the dinosaurian origins of birds.
What do you think the first birds were like?
I envision a hypothetical proto-bird as a rather small, arboreal creature, the size of a small lizard and weighing less than a couple of pounds, with feathers or proto-feathers. It would have used all four legs to jump from branch to branch and parachute, and then began gliding and active flight.
Some recent dinosaur fossils from China have a downy, featherlike covering. Doesn't that prove a link between dinosaurs and birds?
People have accepted that these filamentous structures—dino fuzz—represent proto-feathers. But these things do not resemble feathers, and I don't think they have anything to do with feathers. To me, they look like preserved skin fibers.
The difference between feathers and scales is very, very small. You can transform bird scutes [the scales on bird feet] into feathers with the application of bone morphogenic protein. So while people imagining models for the evolution of feathers feel that filaments must be an intermediate step between scales and feathers, you really don't need that stage.
What about all the other evidence for feathered dinosaurs?
When we see actual feathers preserved on specimens, we need to carefully determine if we are looking at secondarily flightless birds that have retained feathers and only superficially resemble dinosaurs, or if the specimens are in fact related to dinosaurs.
http://discovermagazine.com/2003/feb/breakdialogue
He also said:
quote:
Is there anything that would convince you birds really did evolve from dinosaurs?
At the time period when birds are thought to have evolved, there are plenty of theropod dinosaurs, but they do not have the key birdlike features. Finding a feathered dinosaur that lived earlier, during the late Triassic, would be very convincing. Until we discover the critical specimens, the issue will never be laid to rest.
I would ask about the heart issue.
Can crocodiles hearts (which are like birds) be said to resemble the dinosaurs PaulK mentioned as ancestors?
Can Crocodiles (I'm thinking of their ancestors) be said to be in a vertical line that dates AFTER the dinosaurs PaulK mentioned?
Or.
Can Crocodiles (ancestors) be said to be in a horizontal line with the dinosaurs PaulK mentioned?
(They seem to be in a vertical line that pre-dates PaulK's theropod dinosaurs.)
Parallel issues to help illustrate my point:
(Butterfly issue)
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Visiting a colleague in Germany in 2012, Boston College Research Professor Paul K. Strother was examining soil samples for pollen, spores, pieces of plants and insect legs - organic debris that might otherwise have been considered "pond scum" when it was trapped in sediment during cataclysmic earth events 200 million years ago.
The slides of rock samples drilled in the German countryside included some material that looked familiar to Strother, a Department of Earth and Environmental Sciences researcher at Boston College's Weston Observatory, who studies the origin and early evolution of land plants. What he saw were features similar to those found in insect wings.
The wrinkle was that these types of moths and butterflies - known as Lepidoptera - were long posited to have evolved 50 to 70 million years later, during the Cretaceous period when the first flowering plants emerged as their prime food source.
"The consensus has been that insects followed flowers," said Strother, a co-author of "A Triassic-Jurassic window into the evolution of Lepidoptera," a new report published today in Science Advances. "But that would be 50 million years later than what the wings were saying. It was odd to say the least, that there would be butterflies before there were flowers."
Five years later, Strother and colleagues from natural history museums in Germany and a university in the Netherlands have developed a scientific case showing the Lepidoptera evolved earlier than previously established - emerging during the Jurassic period.
Absent flowers, the researchers report, primitive moths and butterflies, known as the Glossata, developed the physical attributes - namely the sucking proboscis - to find nutrition by drawing off water droplets from the tips of immature gymnosperm seeds.
"What we've found is that these butterflies and moths with mouth parts were feeding on pollen droplets of gymnosperm seeds - from conifers related to pines, seed plants without fruits and flowers. They were feeding off the cone-borne seeds - mainly as a source of water," said Strother.
Even Charles Darwin called the mysterious evolution of flowering plants "an abominable mystery." Scientists have reckoned that flowering plants preceded the insects that fed off of them. But researchers have gradually started to piece together evidence that moths and butterflies existed earlier than the Cretaceous period, which began 145 million years ago
https://phys.org/...sts-evolution-which-came-first.html#nRlv
What a difference some single discovery makes!
caffeine said:
quote:
The key point is that, although fossils sometimes are indeed found which mean groups of animals must have been around longer than we thought, this is not relevant to your point. Birds evolved from terrestrial animals; so they could not have predated them.
But flying reptiles might have been marine (or from the environment)
And during a time when almost all non-insect life was still marine.
quote:
The metacarpal bone allowed a broader wingspan that proved more useful for the terrestrial environment where the specimen was found. It changed how the ancient beast walked and flew in its surroundings, Andres said, and allowed more wing shapes that were good for adapting to various environments.The fossil fragments also challenged a long-held hypothesis that the pterodactyloid originated and thrived in marine environments.
Clark said that researchers hypothesized that pterodactyloids were mainly a marine group because they leaned heavily on specimens found in marine environments. Turns out, Clark explained, this was because the pterodactyloid’s brittle skeletons can be easily preserved in quiet, unhurried waters along a seashore.
On land, the large, hollow bones of a pterodactyloid face being crushed under millions of years of sediment build-up or disturbed by energetic rivers that can easily chew things up, Clark added.
https://www.pbs.org/...evolution-gap-ancient-flying-reptiles
The jury is still out.
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