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Terra Avis; and yet another project
Topic Started: Jan 8 2009, 05:03 PM (2,049 Views)
Carlos
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In addition to Terra Alternativa (not finished yet) and to WIW (also not finished), I present you another of my twisted alternate worlds. This one is almost finished; I just need to present individual species/clades.

The following is an "introduction", if you wish:
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Terra Avis (Terra=Earth, Avis=Bird) is my speculation of how a world dominated by birds would look like. It diverged from our world in the K-T boundary, after the disappearence of dinosaurs, pterosaurs, and non-neornithe birds. Mammals survived, but there are no true marsupials nor placentals, just basal therians, monotremates and the flying volaticotheres; none of these groups achieved dominance over the terrestrial megafauna niches, though monotremates (and some otter like therians) gave rise to quite large aquatic forms and volaticotheres occur in most landmasses; shrew and mustelid like therians occur in the northern landmasses. Reptiles like crocodiles, tortoises and some big lizards and tuataras did produced large forms, but, just like on our Earth, they are also limitated. Instead, it were neornithes, the pioners of archosaur success, that, in terms of diversity, species count and biomass, became the ultimate rulers of the world.

On land, the vast forests and grasslands are inhabited by huge flocks of fast, flightless grazers and browsers. Ratites, during the Paleogene, took most of these niches; ostriches were dominant in Eurasia, but afterwards they lost ground for invaders from Africa and North America: large, flightless galliformes and gruiformes respectively. Today, however, ostriches still are common, with 9 species in Eurasia and Africa and 3 in the Americas. Rheas were dominant in South America for most of the Cenezoic, but the Great Faunal Interchange caused their demise, with now as much as 3/4 species, barely more than in our world. In Oz, cassuwaries, isolated from the other landmasses, still remain the dominant omnivores, though emus were largely replaced by anseranatids; kiwis also occur outside of New Zealand, having produced "avian echidnas" (whereas monotremates produced mole like forms, which birds never did). Flying paleognaths still exist as well, besides the obvious tinamous, there's also rail, shorebird and mesite like lithornids (none of these are present on present Terra Avis).

Galloanseres, composed of Anseriformes and Galliformes, which proved to be very adaptable on our world, achieved major roles in megafaunal niches. Pheasants took the niches in our world occupied by pigs and large rodents in Eurasia (in the Americas they were taken by turkeys, curassows and tinamous, and in Oz by megapodes), while peafowl relatives became antilope analogues in Africa and southern Eurasia; guinea fowl produced both mountain dweelers and a bird's answer to a black rhino (convergently similar to the Australian cassuwaries). Anseriformes, besides familiar waterfowl, large browsers and grazers; South America has giant screamers as the main browsers, nearly all continents have large flightless geese browsing and grazing, and Oz has dromornids; there's also some waterfowl that became fligthless divers, the avian analogues of manatees and dugongs. Oz also has fast running, grazing relatives of the magpie goose. On islands like Madagascar and New Zealand, ratites are the main browsers, but waterfowl are the main grazers.

In the seas, the absence of sea mammals (aside from beaked whale like monotremates and leopard seal like therians in the poles) allowed birds to diversify, though they never produced fully marine forms, since they still need to lay eggs. Penguins and plotopterids are the dolphins and seals of Terra Avis, with cormorants, loons and auks as smaller fish hunters. In the absence of baleen whales pelicans and swanmingoes (derived flamingoes that resemble swans) taking the main filter feeding niches; while they haven't produced flightless forms, they are still huge, the biggest reaching 8 meters of wingspan. Gannets and boobies are also more diverse than on our Earth, and so are tropicbirds (there's no frigate birds on Terra Avis).

The predatory niches are occupied by Acciptriformes and Strigiformes; owls produced flightless, cat like forms, while large eagles similar to the Haast's eagle occur all over the world, and flightless relatives of the secretary bird dominate the plains of Eurasia and Africa; a similar niche is occupied by phorusrhacids in the Americas. Bear and hyena analogues are either flightless vultures or New World vultures, with caracaras, herons/storks and ravens being small oportunists.

Mousebirds are common arboreal birds, the squirrels of TA, while hoatzins have produced "sloth birds". Parrots take similar niches to those of primates; ironically, though, they haven't produced a grassland dweeling form akin to hominids. That niche was taken by ground hornbills, which might produce a future sophont
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Venatosaurus
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Very nice. Two questions though
.Do some of the birds have digits in their wings, like the sloth bird.
.Are the avian echidnas similar in appearance to the Spink from TFIW
Edited by Venatosaurus, Jan 8 2009, 05:29 PM.



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Carlos
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-No, all neornithes have the regular, stiff digits on their hands: a thumb and two other fingers fused

-No, they're just kiwis with quills
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Venatosaurus
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Oh I see. Though still a cool idea, unfortunately the birds will have somewhat repetetive body designs, a little boring, but is still something can catch anyones attention.



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Livyatan


I'm assuming you are avoiding making quadrupedal birds, which makes me happy.
The grand Livyatan on deviantArt: link

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Carlos
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Yes; in fact, I would be an hypocrite if quadrupedal birds were common, since I'm personaly opposed to them. However, my pterosaur-birds (basically frigate bird like tropicbirds, only quite huge; their name comes from their similarities with ornithocheirids and pteranodontids, due to their head crests, huge size, and ecological niches taken) do use their wings as extra legs; however, just like bats and petrels, they are very clumsy on the ground, and thus there's no risk of fully terrestrial, quadruped avians to evolve
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Mei long
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JohnFaa
Jan 8 2009, 05:03 PM
In the absence of baleen whales pelicans and swanmingoes (derived flamingoes that resemble swans) taking the main filter feeding niches; while they haven't produced flightless forms, they are still huge, the biggest reaching 8 meters of wingspan.
Good choice on this one. About 8 meters is very close to the theoretical maximum of flying birds. Argentavis magnificens, the biggest known flying bird, had the wingspan of about 7-7,6 meters, and must have weighed almost 100 kilos.

Pterosaurs could grow larger, though, because they had bigger wing area compared to their size, the quadrupedal posture helped jumping when trying to get to the air, and the hind limbs weren't dead weight when flying but actually helped.
If I made a project like this, I would rather let pterosaurs live. They are simply more interesting and variable than birds.
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Carlos
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True, but even they had their limitations; its unlikely, for instance, for pterosaurs to develop marine forms like penguins, since birds already started doing that in the Cretaceous and pterosaurs never produced diving forms, probably because their wing membranes would make them loose their body heat very quickly when on the water. Plus, while carrion eating pterosaurs are known (Istiodactylus and friends), an eagle like pterosaur would probably not appear, since they used their mouth to catch prey, not their talons
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Livyatan


Mei long
Jan 10 2009, 09:45 AM
JohnFaa
Jan 8 2009, 05:03 PM
In the absence of baleen whales pelicans and swanmingoes (derived flamingoes that resemble swans) taking the main filter feeding niches; while they haven't produced flightless forms, they are still huge, the biggest reaching 8 meters of wingspan.
Good choice on this one. About 8 meters is very close to the theoretical maximum of flying birds. Argentavis magnificens, the biggest known flying bird, had the wingspan of about 7-7,6 meters, and must have weighed almost 100 kilos.
Actually, it is now believed that birds like Argentavis were most likely flightless and that any flight would have been attained by jumping off cliffs, etc.
The grand Livyatan on deviantArt: link

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Carlos
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Teratorns like Argentavis seemed to had been a bird's answer to an azhdarchid: they spent most of their time in the ground, and took off when needing to cover larger distances. Their wings were as big in proportion to their sizes as those of galliformes, although they wouldn't take off in the same way, as they were too big for that.

Pseudodontorns like Osteodontornis reached similar wingspans, which are interestingally the average wingspans for ornithocheiroid pterosaur, with only a few exceptions like Ornithocheirus and Pteranodon being larger. Like them, they were dynamic soarers, using the marine air currents, rather than wing power, to stay aloft.

Swanmingoes to are dynamic soarers, though pelicans are static soarers, just like teratorns
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Mei long
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JohnFaa
Jan 10 2009, 10:34 AM
True, but even they had their limitations; its unlikely, for instance, for pterosaurs to develop marine forms like penguins, since birds already started doing that in the Cretaceous and pterosaurs never produced diving forms, probably because their wing membranes would make them loose their body heat very quickly when on the water. Plus, while carrion eating pterosaurs are known (Istiodactylus and friends), an eagle like pterosaur would probably not appear, since they used their mouth to catch prey, not their talons
Yeah, that's true.
But they could have evolved new adaptations, if they were to live longer. Flightless pterosaurs could have lost their wing membranes and later become aquatic.
And to hunt like an eagle or hawk, a pterosaur would not necessarily have to have strong talons. It would kill prey with their beaks/snouts/teeth, whatever they should be called. I think the lack of terrestrial environment pterosaurs is mostly just because they haven't fossilized nearly as often as marine species.
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Carlos
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Mei Long
 
lack of terrestrial environment pterosaurs


You must be kidding; we have plenty of terrestrial pterosaur taxa. Azhdarchids, dsungaripterids, tapejarids, istiodactylids and some basal pterosaurs like Dimorphodon and the anurognathids were all terrestrial (dsungaripterids had strong terrestrial adaptations and lived in inland areas, though they were likely mollusc eaters; ctenochasmatoids like Pterodactylus seemed also to had been gracefull on land, but they lived mostly on aquatic environments and lived off aquatic invertebrates)
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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Venatosaurus
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It's a shame your not including quadrapedal birds. I believe if pushed by certain ecological occurences, they could become quadrapedal, especially if bearing much weight. I know many things on this site (the japanese site that I'll link) are implausible , but I actually liked the way they tackled quadrapedal birds. It's not impossible, but just unlikely (to happen now of in the future, alternate bird dominant earth, well that may be a different story)

Just translate ;)
http://www.geocities.co.jp/NatureLand/5218/w-500.html

http://translate.google.com/translate?sourceid=navclient&hl=en&u=http%3a%2f%2fkawa3104.at.infoseek.co.jp%2fgigantosaurorunisu.html
Edited by Venatosaurus, Jan 18 2009, 09:17 PM.



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Carlos
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Well, birds as a whole would have lots of trouble in adquiring a quadrupedal stance, specially due to their hand and arm structure. To keep plausability, I only have the pterosaur birds as being "quadrupedal", and possibly some tree climbing birds using clawed wings to climb
Lemuria:
http://s1.zetaboards.com/Conceptual_Evolution/topic/5724950/

Terra Alternativa:
http://s1.zetaboards.com/Conceptual_Evolution/forum/460637/

My Patreon:

https://www.patreon.com/Carliro

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ATEK Azul
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has any body on this site thought about making quadropedal birds from say archeoptyrix or the opposite birds(i forgot the scientific name).
I am dyslexic, please ignore the typo's!
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