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Dremmer
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It's is believed by scientists that they came from reptiles, but could they have come from birds? A primitive mammal, the platypus closely resembles a bird. It can lay eggs. Could hair have evolved from feathers?
Dremmer said:It's is believed by scientists that they came from reptiles, but could they have come from birds? A primitive mammal, the platypus closely resembles a bird. It can lay eggs. Could hair have evolved from feathers?
Borek said:That would require mammals to be younger than birds, as far as I know, they are older.
SW VandeCarr said:Could have? Who knows? It's very unlikely that they actually did. Do you have a reference for this interesting hypothesis?
Dremmer said:It's is believed by scientists that they came from reptiles, but could they have come from birds? A primitive mammal, the platypus closely resembles a bird. It can lay eggs. Could hair have evolved from feathers?
Dremmer said:There are many features that birds and mammals share that do not exist in reptiles.
Dremmer said:There are many features that birds and mammals share that do not exist in reptiles.
Drakkith said:Such as?
Oh, I could go on and on, and I haven't even started yet on the postcranial skeleton or the internal anatomy. "Homology does not necessarily indicate common ancestry?" Get an education in science rather than cut and pasting from creationist factoid websites
paleobarbie said:Oh, I could go on and on, and I haven't even started yet on the postcranial skeleton or the internal anatomy. "Homology does not necessarily indicate common ancestry?" Get an education in science rather than cut and pasting from creationist factoid websites
paleobarbie said:Why yes, I could, but this view is difficult (perhaps intentionally?) The thylacine is the upper skull as it clearly lacks the enlarged carnassial tooth (fourth premolar) of the wolf, as seen in all placental mammals in the order Carnivora (unless secondarily modified, as in the panda). The thylacine also has the marsupial pattern of 3 premolars and 4 molars. The wolf has at least 4 premolars that we can see in this view (unlike any known marsupial)
If we had other views, we could see many more differences. For example, the number of incisors. A total of six above and six below in the wolf (as in most placentals) as opposed to 10 above and 8 below in the thylacine (as in most marsupials).
If we were to view the lower jaw from the back, we would see that the thylacine had a distinct inturned flange on the base of the jaw, a distinctive feature of all marsupials, lacking in all placentals.
If we were to view the skulls from the palate (i.e., the top part of the skull turned upside down) we would see that the thylacine had holes in the palatal bones, typical of marsupials, not seen the wolf.
If we were to look in detail at the way that the bone arching below the eye was formed at the point of the jaw articulation, we would see that a certain bone (the jugal) formed part of the articulation for the jaw, as in all marsupials, but not in the wolf, as typical for placentals. (Actually you can see this if you look carefully)
If we viewed the skull from above we would see that the nasal bones of the thylacine formed a diamond shape at their posterior border, typical of marsupials, as opposed to the rectangular shape in the wolf typical of placentals. Oh, I could go on and on, and I haven't even started yet on the postcranial skeleton or the internal anatomy.
paleobarbie said:"Homology does not necessarily indicate common ancestry?" Get an education in science rather than cut and pasting from creationist factoid websites
paleobarbie said:PS. Things that birds and mammals share (to the exclusion of reptiles) are clearly convergences due to both being warmblooded, no problem there. (E.g., single aorta, but on the left in mammals, the right in birds, clearly derived independently.)
While this is a common question, the current scientific understanding is that mammals and birds evolved from a common ancestor, but not from each other. The earliest known mammals and birds appeared around the same time period, but they evolved separately and developed different characteristics and adaptations.
One of the main pieces of evidence is the presence of similar genetic sequences and developmental pathways in both mammals and birds. Additionally, fossil records show that both groups evolved from a common reptilian ancestor and share some physical characteristics such as warm-bloodedness and the presence of hair or feathers.
While there are no known transitional fossils directly linking birds and mammals, there are transitional fossils of early mammal-like reptiles and early bird-like dinosaurs. These fossils show a gradual transition of traits and characteristics between the two groups, supporting the idea of a common ancestor.
Mammals and birds have distinct differences in their skeletal structures, reproductive systems, and respiratory systems. Mammals have a single jaw bone and three middle ear bones, while birds have a single middle ear bone and a unique skeletal structure for flight. Additionally, mammals give birth to live young and have mammary glands for nursing, while birds lay eggs and do not have mammary glands.
The process of evolution is not linear and there is no guarantee that any two species will evolve from each other in the future. However, it is highly unlikely that mammals and birds will evolve from each other as they have already evolved separately for millions of years and have developed distinct and successful adaptations for their respective environments.