Historum - History Forums  

Go Back   Historum - History Forums > Themes in History > Natural Environment
Register Forums Blogs Social Groups Mark Forums Read

Natural Environment How Human History has been impacted by the environment, science, nature, geography, weather, and natural phenomena


Reply
 
LinkBack Thread Tools Display Modes
Old August 16th, 2017, 05:19 AM   #11
Historian
 
Joined: Jan 2013
From: Anywhere
Posts: 1,170

Quote:
Originally Posted by Corvidius View Post
Yes, of course there is no answer at this point in time, and may never be.

An indication of the confusion about where some maniraptorans fit on the gladogram, and so their potential to be in, or close to the direct line, if there is one, that led to modern Aves, is shown in Fastovsky and Weishampel. Rahonavis is described as being a member of troodontidae, and then a little further on it appears on the cladogram just past Archaeopteryx [typos not allowed?] , under avialae. It is still not 100% clear if Rahonavis could in fact be a dromaeosaur, and Archaeopteryx, depending on what author you read, moves between being a dromaeosaur and part of avialae. At the moment it is generally regarded as just being a part of avialae, which came from.....

Maybe the closest it is possible to come, without going back further than maniraptora, is to say that any maniraptoran that could be described as being a member of paraves, but which cannot with confidence be put specifically into either of the two parts of deinonychosauria, and being earlier than Archaeopteryx, is a good contender. Rahonavis is later than Archaeopteryx so is not a contender, but is a good example of the difficulty of putting some of these maniraptorans into a specific group.
May I say something (even though its bit of a minor sidetrack). A friend of mine named Stanton Funk who does drawings of prehistoric animals in DeviantArt has first told me of a bird named Qianshanornis. So what's so fascinating about this Paleocene bird is that it has a claw similar to that of either a Dromeosaur or Troodontid (of course there's the Cassowary that has a middle long claw). However! These birds from the Paleocene, Eocene, Oligocene, and Miocene epochs were still primitive and has retain of a few similar features as their non-avian ancestors. Like lets look at Qianshanornis and Pelagornis. Once we look at their fossils at first glance one looks like a small raptor and the other a pterosaur due to its pseudooothed beak. But of course they are both birds. (But its noting that after the non-avian dinosaurs were gone, the avian-dinosaurs that survived the Late Cretaceous that went onto living in the Paleocene along with Choristodera and Crocodilia able to keep of the primitive features of Maniraptorans while new species evolved and thrived among their older cousins in the Paleocene epoch were they had the abundant of available land as large mammals didn't exist on the epoch. With large birds starting to evolve like Gastornis which kept a small tail.)
Fossilworks: Qianshanornis
http://www.tandfonline.com/doi/abs/1...34.2013.748059
https://en.m.wikipedia.org/wiki/Qianshanornis
Now back to the Maniraptorans. As birds are clearly a direct succession and continuation of Maniraptorans. But do you think that they should be closer to Troodontids rather than Dromeosaurs or vice versa
Azarius Balios is offline  
Remove Ads
Old August 16th, 2017, 05:56 AM   #12

Corvidius's Avatar
Historian
 
Joined: Jul 2017
From: Crows nest
Posts: 1,703

Quote:
Originally Posted by Azarius Balios View Post
Now back to the Maniraptorans. As birds are clearly a direct succession and continuation of Maniraptorans. But do you think that they should be closer to Troodontids rather than Dromeosaurs or vice versa
I think that all the avialans living right up to K-Pg were descended from a mix of deinonychosaurs, and perhaps the basal maniraptor that gave rise to both groups within deinonychosauria. So maybe three lines of parallel evolution, though not all necessarily surviving to K-Pg. I doubt this will ever get disentangled with a great deal of confidence.

On my personal opinion, if modern birds did not come directly from a basal maniraptor that gave rise to Troodontids and Dromeosaurs, but was not in either group, and such an ancestor cannot be seen at this time, then I think Troodontids are more likely to be the origin of the modern bird than Dromeosurs. The flying/gliding Dromeosaurs such as Archaeopteryx, if it is also a Dromeosaur as well as an avialan, and Microraptor, seem less an ancestor than the Troodontid Rahonavis, which looks closer to a modern bird.

So, if forced at gunpoint to make a definitive statement, then I would say the modern bird is an offshoot of troodontids, but don't shoot me if I'm wrong.

But then, if Deinonychosaurs are secondarily flightless, and I'm not convinced of this at all, but some are, then that may well make a basal maniraptor a flyer of some type, and Deinonychosaurs being an offshoot of what became modern birds. Chicken and egg, confusing.....

Last edited by Corvidius; August 16th, 2017 at 06:10 AM. Reason: typos, amendments
Corvidius is offline  
Old August 16th, 2017, 08:15 AM   #13

AlpinLuke's Avatar
Knight-errant
 
Joined: Oct 2011
From: Lago Maggiore, Italy
Posts: 22,670
Blog Entries: 19

Flying or not flying bird?

It's a pivotal point. Today there are birds which don't love to fly [like the ducks of my beloved lake] and birds which cannot fly [like ostriches].

The answer to this question changes a lot the context.
AlpinLuke is online now  
Old August 16th, 2017, 09:03 AM   #14

oshron's Avatar
Rplegacy Emperor
 
Joined: Jun 2009
From: western Terranova
Posts: 3,690

Quote:
Originally Posted by Naomasa298 View Post
Surely the First Bird is Ivanka Trump.

Strictly non-politically.

Quote:
Originally Posted by AlpinLuke View Post
Flying or not flying bird?

It's a pivotal point. Today there are birds which don't love to fly [like the ducks of my beloved lake] and birds which cannot fly [like ostriches].

The answer to this question changes a lot the context.
not really. while most birds can fly, to the point it's specifically noted when they can't but not when they can, it's not the be-all end-all of what makes a bird a bird. like, does being able to fly mean that a bat is a bird and not a mammal?
oshron is offline  
Old August 16th, 2017, 09:15 AM   #15

AlpinLuke's Avatar
Knight-errant
 
Joined: Oct 2011
From: Lago Maggiore, Italy
Posts: 22,670
Blog Entries: 19

Quote:
Originally Posted by oshron View Post


not really. while most birds can fly, to the point it's specifically noted when they can't but not when they can, it's not the be-all end-all of what makes a bird a bird. like, does being able to fly mean that a bat is a bird and not a mammal?
A bat is a mammal and not a bird because it reproduces itself without eggs.

Eggs are essential to define a species "bird". No eggs ... no birds.
AlpinLuke is online now  
Old August 16th, 2017, 09:33 AM   #16
Historian
 
Joined: Jan 2013
From: Anywhere
Posts: 1,170

Quote:
Originally Posted by Corvidius View Post
I think that all the avialans living right up to K-Pg were descended from a mix of deinonychosaurs, and perhaps the basal maniraptor that gave rise to both groups within deinonychosauria. So maybe three lines of parallel evolution, though not all necessarily surviving to K-Pg. I doubt this will ever get disentangled with a great deal of confidence.

On my personal opinion, if modern birds did not come directly from a basal maniraptor that gave rise to Troodontids and Dromeosaurs, but was not in either group, and such an ancestor cannot be seen at this time, then I think Troodontids are more likely to be the origin of the modern bird than Dromeosurs. The flying/gliding Dromeosaurs such as Archaeopteryx, if it is also a Dromeosaur as well as an avialan, and Microraptor, seem less an ancestor than the Troodontid Rahonavis, which looks closer to a modern bird.

So, if forced at gunpoint to make a definitive statement, then I would say the modern bird is an offshoot of troodontids, but don't shoot me if I'm wrong.

But then, if Deinonychosaurs are secondarily flightless, and I'm not convinced of this at all, but some are, then that may well make a basal maniraptor a flyer of some type, and Deinonychosaurs being an offshoot of what became modern birds. Chicken and egg, confusing.....
Ah the classic chicken and the egg.
Hmm! It seems we need to have a closer look at the Paraves (eumaniraptora). Sure it could be that Dromeosaurs,Troodontids, and Avialans evolved from a common (and single) possible ancestor from the Paraves in the late Jurassic. Just as human and chimpanzees evolved from sahelanthropus. So lets find the likely candidate.
Azarius Balios is offline  
Old August 16th, 2017, 09:35 AM   #17

Corvidius's Avatar
Historian
 
Joined: Jul 2017
From: Crows nest
Posts: 1,703

Quote:
Originally Posted by AlpinLuke View Post
Flying or not flying bird?

It's a pivotal point. Today there are birds which don't love to fly [like the ducks of my beloved lake] and birds which cannot fly [like ostriches].

The answer to this question changes a lot the context.
I would say that the ability to fly or not, should not be considered to be a defining character of modern birds. They all show the major flight adaptations, kinetic skull, loss of teeth, a beak, deep keeled sternum, synsacrum, fused digits and pygostyle, so all are true birds.

However, we differentiate between various types of pre extinction maniraptor, flapping, gliding or land bound, into Aves, with all the above characters, and all the others, that don't have the full set. So when we see post extinction the evolution of an undoubted Aves into a terror bird, we are seeing a modern post extinction bird take up the ecological niche vacated by large dromeosaurs like Dakotaraptor and Utahraptor.

Kelenken has arms that are atrophying to almost T.Rex proportions and it's sternum, while still large, is much smaller than needed for large flight muscles. It still has a synsacrum, and it is unlikely that would have reverted back, and also unlikely for it to have re-evolved a long tail. But could it be argued that it is no longer a bird, but a "re-imagined" raptor dinosaur? The same issue exists pre extinction with any maniraptor that does not have the full set of modern Aves characters. Which is a bird and which is not? Is a modern penguin still a bird in the sense we see them, or a highly derived aquatic maniraptor, or both. The only certainty is that it is a maniraptor. But I'm sure a penguin is a bird and that everybody will say it is a bird.
Corvidius is offline  
Old August 16th, 2017, 09:37 AM   #18

oshron's Avatar
Rplegacy Emperor
 
Joined: Jun 2009
From: western Terranova
Posts: 3,690

Quote:
Originally Posted by AlpinLuke View Post
A bat is a mammal and not a bird because it reproduces itself without eggs.

Eggs are essential to define a species "bird". No eggs ... no birds.
then what about lizards? or fish? or crocodiles? or spiders? or the platypus? are they birds, too, because they also lay eggs?
oshron is offline  
Old August 16th, 2017, 10:10 AM   #19

Corvidius's Avatar
Historian
 
Joined: Jul 2017
From: Crows nest
Posts: 1,703

Quote:
Originally Posted by Azarius Balios View Post
Ah the classic chicken and the egg.
Hmm! It seems we need to have a closer look at the Paraves (eumaniraptora). Sure it could be that Dromeosaurs,Troodontids, and Avialans evolved from a common (and single) possible ancestor from the Paraves in the late Jurassic. Just as human and chimpanzees evolved from sahelanthropus. So lets find the likely candidate.
Somewhere in the vicinity of the scansoriopterygids, an ancestor common to them and paraves. One ended up as Yi qi and one as modern birds. Or do we look, without going to far back, to a common ancestor to oviraptors and paraves. The problem with looking at the start of paraves is that named groups and species start at troodontids and dromeosaurs, with Anchiornis flying about between them, but that is seen as a descendant and not an ancestor, depending on who you read, or phase of the Moon, conjunction of the planets.....

Last edited by Corvidius; August 16th, 2017 at 10:19 AM.
Corvidius is offline  
Old August 16th, 2017, 11:19 AM   #20
Historian
 
Joined: Jan 2013
From: Anywhere
Posts: 1,170

Quote:
Originally Posted by Corvidius View Post
Somewhere in the vicinity of the scansoriopterygids, an ancestor common to them and paraves. One ended up as Yi qi and one as modern birds. Or do we look, without going to far back, to a common ancestor to oviraptors and paraves. The problem with looking at the start of paraves is that named groups and species start at troodontids and dromeosaurs, with Anchiornis flying about between them, but that is seen as a descendant and not an ancestor, depending on who you read, or phase of the Moon, conjunction of the planets.....
Not too far back. Just the two you referenced. The scansoriopterygidae and Paraves. Since they are the best to search and make our way. But lets not look far back.
(Sorry if I replied late. Was outside)
Azarius Balios is offline  
Reply

  Historum > Themes in History > Natural Environment

Tags
controversy, first bird



Search tags for this page
Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
In "The Who" song "Squeezebox" who played the banjo?"rite Zheng LaiEn General History 14 July 15th, 2016 08:21 AM
"YES" does not mean "MAYBE", and "Regret"≠"RAPE" Abhishek Philosophy, Political Science, and Sociology 110 January 7th, 2016 04:17 PM
Historical Terminology of "Telangana", "Telugu", and "Andhra" civfanatic Asian History 20 September 28th, 2014 06:41 PM

Copyright © 2006-2013 Historum. All rights reserved.