Reptilian World [IW]

[Flyndaran]

Originally Posted by ericthered

Interesting. I was not expecting such an overwhelming chorus of "crocs!"

I was actually thinking less of a long term "mammals were never here" and more of a "mammals seem to have been here, but aren't here anymore."

That would change things, but in what ways and by how much really depends on how long mammals have been mysteriously gone.

[lwcamp]

Originally Posted by ericthered

Interesting. I was not expecting such an overwhelming chorus of "crocs!"

I was actually thinking less of a long term "mammals were never here" and more of a "mammals seem to have been here, but aren't here anymore."

The sebecosuchians were crocodylomorphs that coexisted with mammals after the dinos died out. For a while they were among the top predators in South America. These guys were fully terrestrial, with steak-knife teeth for slashing prey, and Sebecus proper grew to about twice the weight of the modern Komodo dragon.

Wikipedia references:
http://en.wikipedia.org/wiki/Sebecus
http://en.wikipedia.org/wiki/Baurusuchus

A number of thoer crocodylomorphs have independently evolved to a similar lifestyle to the sebecosuchids, such as Pristichampsus and Quinkana
http://en.wikipedia.org/wiki/Pristichampsus
http://en.wikipedia.org/wiki/Quinkana

And of course crocodylomorphs from the late mesozoic had a wide diversity of forms and lifestyles, including omnivores and herbivores; fully terrestrial and fully aquatic forms (including analogues of dolphins and orcas).

The varanids are another reptilian group that have the potential to really take off. Active, athletic, with many adaptations for high aerobic capacity, you might see these lizards evolving to fit various predatory niches, then radiating into frugivory (like the modern Gray's monitor), and from there to herbivory.

Monstersaurs were apparently once much more varanid-like than today's monsters, which tend to be sluggish nest robbers of hot North American deserts. If the likes of Estesia and Paleosaniwa were still around, they could be quite interesting - like Komodo dragons, but highly venomous.

And speaking of varanid relatives, there's no reason the Mososaurs had to go extinct. These immense sea going predatory lizards could be common in the oceans.

At least one turtle is effectively warm blooded
http://en.wikipedia.org/wiki/Leatherback_turtle
Turtles may be common herbivores and omnivores.

Sphenodonts may be more common. Only two species of sphenodont survive today, but they were once common and diverse.

Then you could throw in long-necked aquatic plesiosaurs and dolphin-like ichtyosaurs for some aquatic variation. Champsosaurs survived the K/T event, but in our timeline went extinct in the Miocene - perhaps in this timeline they could still be kicking around.

In addition to the big charismatic megafauna, you would also have a diversity of smaller, cold blooded forms like today's lizards and snakes, roles that could be held by actual lizards and snakes, as well as various sphenodonts.

Luke

[Refplace]

Originally Posted by Miles

Keep in mind that the current paleontological opinion is that the dinosaurs were either warm-blooded or simulated warm-bloodedness by being freaking huge. Winters would be more active than your would think.


If you wanted to throw the players for a loop, include furry reptiles. In this case the "fur" would actually be a thick pelt of down, without the quill and stem of of typical featers.

These can work together.
A niche of furred reptiles that thrive in colder climes and winter.

[smurf]

http://en.wikipedia.org/wiki/Therapsids

Mammal like reptiles which means they lactated for their young.

I had a race of lizards in my campaign with a back story based on this deviation of evolution.

[Purple Haze]

Originally Posted by smurf

http://en.wikipedia.org/wiki/Therapsids

Mammal like reptiles which means they lactated for their young.

It means nothing of the sort. Therapsids are characterized from their more reptilian ancestors by a more erect posture, more symmetrical feet, and greater differentiation in dentition.

One needs to be way down the tree to mammaliaformes before one can start arguing lactation. Monotremes are outright mammals and they barely do.

[patchwork]

Mega-Anthrax. Anthrax will kill most mammals, no reptiles, and apparently not many birds. A nastier, more virulent form of anthrax might give you this world - making it one of the Plague designates, albeit a weird one. With the death of its primary hosts, it may have died out, but no sane explorer would assume that.

The wide open space in a more-or-less modern ecology that suddenly lost its mammals would seem to be large herbivores. I think you have to start with turtles and go from there. Depending on how much time you have to work with.

[Flyndaran]

Few diseases can last more than a couple of years in "spore" form. I think small pox is unusual for being viable for 30 years in soil.