Freethought & Rationalism Archive

Craig · 04-02-2003, 05:48 PM

Really? Wow that is just cool. I had no idea (obviously).

Guess I need to watch the Discovery channel more to rid myself of my tooth-centric view of poison delivery systems.

Nic Tamzek · 04-02-2003, 05:52 PM

Quote:

This is an echidna. It has one posterior opening only through which is eliminates and reproduces called a cloaca, a characteristic shared only with fish, reptiles and amphibians.

[annoying nerdiness]
Actually IIRC certain early-diverging placental mammals also only have cloacas, like the tenrecs of Madagascar.
[/annoying nerdiness]

Good topic though.

Viti · 04-02-2003, 05:55 PM

Quote:

Originally posted by Craig
Platypus (Platypi? Platypuses?) are venomous? Any guesses as to what that is for? AFAIK they are not carnivorous, and don't have much in the way of teeth so how is the poison delivered?

I didn't know until about 6 months ago...that's why I like these kinds of threads...and yes a spur in the ankle delivers a very painful venom. It's not lethal to people, but causes excrutiating pain that DOESN'T RESPOND TO MORPHINE...can you imagine? The thought is it is used as protection.

Viti · 04-02-2003, 05:58 PM

Quote:

Originally posted by Nic Tamzek
[annoying nerdiness]
Actually IIRC certain early-diverging placental mammals also only have cloacas, like the tenrecs of Madagascar.
[/annoying nerdiness]

Good topic though.

I'll have to look it up, thank you! I had read only the monotremes (platypus and echidna) had this characteristic.

Viti · 04-02-2003, 06:10 PM

Okay I looked it up, and indeed primitive placental mammals in the Tenrec family (some hedgehogs included) have cloaca for elimination...

Thank you for the additional information!

Quote:

Members of Tenrecidae retain a characteristic found in early placental mammals, a cloaca, a common opening for urogenital and rectal tracts. The testes are not descended and it is nearly impossible to tell males from females. http://www.chaffeezoo.org/animals/tenrecs.html

Coragyps · 04-02-2003, 06:38 PM

Quote:

Don't YECs think that *all* snakes are nothing but legless lizards, thanks to god's curse of the serpent in Gen. 3:14?

Some poor YEC goon on one of the forums I visit claimed that dinosaurs were demoted to snakes after one of them tempted Eve with the apple...and he seemed serious about it.

The Lone Ranger · 04-02-2003, 06:44 PM

Are butterflies and moths different kinds? If so, which is this?*

Below is a picture of a Rock Hyrax, Procavia capensis. Adults weigh less than 10 pounds. What kind is it? **

Is the animal in the picture below a snake or a lizard?***

* It's a moth, Pseudopanthera macularia.

** According to its anatomy, morphology, and genetics, its closest living relatives are elephants.

*** Trick question -- it's neither. It's an amphisbaena, a reptile that has characteristics of both snakes and lizards, but is not considered to belong to either of these groups. They're sometimes called "Worm Lizards".

Viti · 04-02-2003, 07:05 PM

Lone Ranger, thanks! I like the Hyrax...are there subspecies or just the one little elephant cousin?

The Lone Ranger · 04-02-2003, 07:22 PM

LadyShea:

There may be subspecies of Procavia capensis, but it's truly unique as a species. Not only is it the only member of its genus, it's the only member of its entire family (Procaviidae) and even of its entire Order (Hyracoidea).

Cheers,

Michael

lpetrich · 04-02-2003, 08:11 PM

That hyrax does not look much like an elephant because their ancestors diverged not long after the K-T mass extinction; fossil elephants start appearing in the Eocene.

Also diverging from hyraxes and elephants at this time are sirenians -- manatees and dugongs, a.k.a. sea cows.

There is also some evidence that elephants and sirenians are closer in another way -- that elephants' ancestors had returned to the water for a while, with sirenians staying there.

So one can reconstruct this sequence:

In the late Cretaceous, Africa/Arabia splits off from the other continents, carrying the ancestors of the "afrotherian" mammals with it. These diverge into the ancestors of aardvarks, golden moles, and elephant shrews -- and the hyrax-elephant-sirenian ancestor, which likely looked much like a present-day hyrax.

But not long after the K/T disaster, some early hyrax-like creature starts living in the water. Some of its descendants return to the land, becoming elephants, and some stay in the water, becoming sirenians.

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04-02-2003, 05:48 PM	#11
Craig Veteran Member Join Date: Feb 2003 Location: Seattle, WA Posts: 1,058	Really? Wow that is just cool. I had no idea (obviously). Guess I need to watch the Discovery channel more to rid myself of my tooth-centric view of poison delivery systems.

04-02-2003, 06:44 PM	#17
The Lone Ranger Veteran Member Join Date: Oct 2001 Location: Eastern U.S. Posts: 1,230	Are butterflies and moths different kinds? If so, which is this?* Below is a picture of a Rock Hyrax, Procavia capensis. Adults weigh less than 10 pounds. What kind is it? Is the animal in the picture below a snake or a lizard?* * It's a moth, Pseudopanthera macularia. According to its anatomy, morphology, and genetics, its closest living relatives are elephants. * Trick question -- it's neither. It's an amphisbaena, a reptile that has characteristics of both snakes and lizards, but is not considered to belong to either of these groups. They're sometimes called "Worm Lizards".

04-02-2003, 07:05 PM	#18
Viti Contributor Join Date: Apr 2001 Location: Down South Posts: 12,879	Lone Ranger, thanks! I like the Hyrax...are there subspecies or just the one little elephant cousin?

04-02-2003, 07:22 PM	#19
The Lone Ranger Veteran Member Join Date: Oct 2001 Location: Eastern U.S. Posts: 1,230	LadyShea: There may be subspecies of Procavia capensis, but it's truly unique as a species. Not only is it the only member of its genus, it's the only member of its entire family (Procaviidae) and even of its entire Order (Hyracoidea). Cheers, Michael

04-02-2003, 08:11 PM	#20
lpetrich Contributor Join Date: Jul 2000 Location: Lebanon, OR, USA Posts: 16,829	That hyrax does not look much like an elephant because their ancestors diverged not long after the K-T mass extinction; fossil elephants start appearing in the Eocene. Also diverging from hyraxes and elephants at this time are sirenians -- manatees and dugongs, a.k.a. sea cows. There is also some evidence that elephants and sirenians are closer in another way -- that elephants' ancestors had returned to the water for a while, with sirenians staying there. So one can reconstruct this sequence: In the late Cretaceous, Africa/Arabia splits off from the other continents, carrying the ancestors of the "afrotherian" mammals with it. These diverge into the ancestors of aardvarks, golden moles, and elephant shrews -- and the hyrax-elephant-sirenian ancestor, which likely looked much like a present-day hyrax. But not long after the K/T disaster, some early hyrax-like creature starts living in the water. Some of its descendants return to the land, becoming elephants, and some stay in the water, becoming sirenians.

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