Noah's Ark Zoo
Apparently this bunch of clowns has won a Quality Badge for "Learning Outside The Classroom". Except, as noted by several people, its got a somewhat questionable attitude to science. Its a creationist zoo. You have to dig fairly deep to get to the creationist stuff, and its probably something they aren't allowed to mention too much in their school visits, the worksheet on "Adaptation" doesn't mention evolution, but at KS2 (7-12 year olds) you wouldn't really expect it to. However there's no mention of evolution or classification as subjects in either the GCSE (15-16 year olds) or AS/A-Level (17-18) workshops. Animal welfare, conservation, genetics and farming all get mentioned, but not evolution or biodiversity. I wonder why.
Of course by the time you've got to this section you'll have noticed the red section marked "Evolution and Creation". Guess which side of the fence they sit on. Taking their stance on the difference between reptiles and mammals we can see that they're both factually incorrect, and creationist (I know, I know, hardly unusual), but they wouldn't be demanding that mammals and reptiles were so radically different if they weren't trying to push their agenda. SO I'll push mine back a little.
1. Reptiles have horny or scaly skin. Mammals have fur or hair.
True. Fur is one of the defining features of mammals. But fur and scales are both made from keratin. (Alpha and Beta keratin in the case of reptiles. Alpha keratin only in the case of mammals)
2. Mammals have a single type of skin cell for colour. Reptiles have 3 types of skin cell for colour.
Well, given that they have different skin structures- reptiles having scales and mammals a glandular skin I'm not surprised. But these are modern mammals, and modern reptiles we're talking about here. The last common ancestor between the two groups would have been about 300 million years ago. (Although Noah's Ark don't accept this dating methodology).
3. Reptiles have low metabolism and require less energy. Mammals have high metabolism.
4. The body temperature of reptiles varies according to their environment (they are 'cold-blooded'). Mammals are able to maintain a constant temperature (they are 'warm-blooded').
Birds also have a high metabolism. And beta keratin. And not all reptiles are cold-blooded. Leatherback turtles can maintain a body temperature above that of their environment. So do Tuna and Great White Sharks. There was a nice paper in Science that showed that the mosasaurs, plesiosaurs and pliosaurs were very probably warm-blooded.
5. Reptiles (but not tortoise/turtles, snakes or crocodilians) have a "third eye", known as a parietal or pineal eye. It has a cornea, lens and photoreceptors. Mammals have only a parietal gland, used for endocrine production.
So that's the Tuatara, and the lizards that aren't snakes then. If its been lost in crocs, turtles and snakes why not mammals? Lineages lose features through evolution all the time. Whales don't have external back legs. Stellar's Sea Cow didn't have any fingers. So what?
6. Reptiles have small, relatively even teeth with single roots; they are replaced often. Mammals have different types of teeth with multiple roots - incisors, canines, premolars and molars - and replace their teeth only once.
And we have a sequence of fossils that show how this feature was acquired. And while reptiles don't have quite the variety of tooth morphology in their jaws that mammals do there's still a fair amount going on. Look at a T. rex jaw, there are big teeth and little teeth, and they're in different parts of the jaw doing different things. But the main reason this is important is because mammals, and their more reptilian ancestors evolved chewing. Most reptiles don't chew. And you need to have your teeth occluding properly to be able to chew effectively. To do that you can't be replacing teeth continuously, you'd have gaps all over the place. So continuous replacement doesn't become an option, but diversification of tooth morphology is suddenly a very real proposition.
7. Reptiles have 3 bones in the lower jaw: the dentary (holding the teeth), the quadrate and the articular. Mammals have only one lower jaw bone.
8. Reptiles' ears have only one bone, the stapes. Mammals have 3 bones, (stapes, malleus, incus), and the very complicated organ of Corti.
These two are again closely related. The malleus and the incus are the quadrate and the articular. Again there's a whole series of fossils that you can follow showing how the jaw joint became involved in hearing and the dentary enlarged and a new jaw joint evolved. One lovely name for an early mammaliaform (now sunk into synonomy more's the pity) was Diarthrognathus or "Two Jointed Jaw", because that's exactly what it had, a quadrate/articular joint and a dentary/squamosal one.
9. The reproductive system of male reptiles includes a hemi- penis. This consists of two penises, which are used singly and repeatedly to fertilise several of a female's eggs.
And most birds don't have penises at all (ducks are an occasionally quite frightening exception). Penises come and go, grow bones and lose them, are co-opted from all sorts of different tissues and structures.
10. Most reptiles lay eggs. Mammals do not.
ALERT! ALERT! TAXONOMY FAIL! One word. Monotremes. Platypuses and Echidnas lay eggs.
11. Reptiles do not usually guard their eggs or care for their young. Mammals all have milk glands and suckle their young.
Again milk production is one of the defining features of mammals. Its in the name! Sadly we can't see how it appeared, because the tissues don't fossilise. I don't see how its a problem. Birds have feathers.But they're still vertebrates.
12. The sex of the unborn young of reptiles is determined by external temperature. Hot temperatures result in more females.
Only in some reptiles. In others it is determined by genes. And in birds its a gene. Interestingly there are some similarities between the sex determining genes of birds and monotremes. Evidence (along with the egg thing) of shared ancestry between the two groups.
13. Mammals breathe by way of a diaphragm in their chest (the thorax). Reptiles have no diaphragm and breathe very differently, with their cheeks and mouth.
And in the case of alligators and crocodiles with a through-flow system like that of birds.
14. Reptiles have a 3-chambered heart, except crocodilians which, like mammals, have a 4-chambered heart. Since their hearts cannot pump blood far upwards, reptiles move close to the ground (they 'creep').
Eh? I wouldn't describe a Komodo Dragon as "creeping". But as reptiles don't have a high metabolism they don't need so much oxygen, so they don't need to separate the two halves of the heart (and very little mixing of oxygenated and deoxygenated blood actually goes on thanks to complex valves). Even with their more inefficient hearts reptiles can be pretty active when they want to be.
15. The legs of reptile are splayed out from the body. The legs of mammals are positioned under the body.
Except for dinosaurs (including birds), lots of early crocodiles, modern crocs in a hurry. Oh, and Platypuses and Echidnas. They have a sprawling gait too. But aren't they mammals?
I've actually been trying to work out what kind of creationists the Noah's Ark Zoo people are. They don't seem to accept that the world is 6,000 years old, like AiG do. But they certainly don't like the answer radiometric dating gives. And most bizarre of all is their take on the fossil record- it records the recolonisation of the world after the flood with animals and plants, and as each group became abundant enough to fossilise that's when it turned up in the rock record, despite always having been there. Its a hideous fudge that isn't obviously your typical YEC stuff, and as such means I'm sure these guys are vilified by the AiG crowd. And yet its also at odds with reality. As someone on Pharyngula said "halfway between right and wrong is still wrong".
Oh and that cool new paper on hot-blooded mosasaurs? Your reference is:
Bernard, A. et al. (2010) Regulation of Body Temperature by Some Mesozoic Marine Reptiles. Science, 328, 1379 - 1382
Oh, and you know what really sticks in my craw? The Horniman Museum doesn't have a badge. Bastards.
Of course by the time you've got to this section you'll have noticed the red section marked "Evolution and Creation". Guess which side of the fence they sit on. Taking their stance on the difference between reptiles and mammals we can see that they're both factually incorrect, and creationist (I know, I know, hardly unusual), but they wouldn't be demanding that mammals and reptiles were so radically different if they weren't trying to push their agenda. SO I'll push mine back a little.
1. Reptiles have horny or scaly skin. Mammals have fur or hair.
True. Fur is one of the defining features of mammals. But fur and scales are both made from keratin. (Alpha and Beta keratin in the case of reptiles. Alpha keratin only in the case of mammals)
2. Mammals have a single type of skin cell for colour. Reptiles have 3 types of skin cell for colour.
Well, given that they have different skin structures- reptiles having scales and mammals a glandular skin I'm not surprised. But these are modern mammals, and modern reptiles we're talking about here. The last common ancestor between the two groups would have been about 300 million years ago. (Although Noah's Ark don't accept this dating methodology).
3. Reptiles have low metabolism and require less energy. Mammals have high metabolism.
4. The body temperature of reptiles varies according to their environment (they are 'cold-blooded'). Mammals are able to maintain a constant temperature (they are 'warm-blooded').
Birds also have a high metabolism. And beta keratin. And not all reptiles are cold-blooded. Leatherback turtles can maintain a body temperature above that of their environment. So do Tuna and Great White Sharks. There was a nice paper in Science that showed that the mosasaurs, plesiosaurs and pliosaurs were very probably warm-blooded.
5. Reptiles (but not tortoise/turtles, snakes or crocodilians) have a "third eye", known as a parietal or pineal eye. It has a cornea, lens and photoreceptors. Mammals have only a parietal gland, used for endocrine production.
So that's the Tuatara, and the lizards that aren't snakes then. If its been lost in crocs, turtles and snakes why not mammals? Lineages lose features through evolution all the time. Whales don't have external back legs. Stellar's Sea Cow didn't have any fingers. So what?
6. Reptiles have small, relatively even teeth with single roots; they are replaced often. Mammals have different types of teeth with multiple roots - incisors, canines, premolars and molars - and replace their teeth only once.
And we have a sequence of fossils that show how this feature was acquired. And while reptiles don't have quite the variety of tooth morphology in their jaws that mammals do there's still a fair amount going on. Look at a T. rex jaw, there are big teeth and little teeth, and they're in different parts of the jaw doing different things. But the main reason this is important is because mammals, and their more reptilian ancestors evolved chewing. Most reptiles don't chew. And you need to have your teeth occluding properly to be able to chew effectively. To do that you can't be replacing teeth continuously, you'd have gaps all over the place. So continuous replacement doesn't become an option, but diversification of tooth morphology is suddenly a very real proposition.
7. Reptiles have 3 bones in the lower jaw: the dentary (holding the teeth), the quadrate and the articular. Mammals have only one lower jaw bone.
8. Reptiles' ears have only one bone, the stapes. Mammals have 3 bones, (stapes, malleus, incus), and the very complicated organ of Corti.
These two are again closely related. The malleus and the incus are the quadrate and the articular. Again there's a whole series of fossils that you can follow showing how the jaw joint became involved in hearing and the dentary enlarged and a new jaw joint evolved. One lovely name for an early mammaliaform (now sunk into synonomy more's the pity) was Diarthrognathus or "Two Jointed Jaw", because that's exactly what it had, a quadrate/articular joint and a dentary/squamosal one.
9. The reproductive system of male reptiles includes a hemi- penis. This consists of two penises, which are used singly and repeatedly to fertilise several of a female's eggs.
And most birds don't have penises at all (ducks are an occasionally quite frightening exception). Penises come and go, grow bones and lose them, are co-opted from all sorts of different tissues and structures.
10. Most reptiles lay eggs. Mammals do not.
ALERT! ALERT! TAXONOMY FAIL! One word. Monotremes. Platypuses and Echidnas lay eggs.
11. Reptiles do not usually guard their eggs or care for their young. Mammals all have milk glands and suckle their young.
Again milk production is one of the defining features of mammals. Its in the name! Sadly we can't see how it appeared, because the tissues don't fossilise. I don't see how its a problem. Birds have feathers.But they're still vertebrates.
12. The sex of the unborn young of reptiles is determined by external temperature. Hot temperatures result in more females.
Only in some reptiles. In others it is determined by genes. And in birds its a gene. Interestingly there are some similarities between the sex determining genes of birds and monotremes. Evidence (along with the egg thing) of shared ancestry between the two groups.
13. Mammals breathe by way of a diaphragm in their chest (the thorax). Reptiles have no diaphragm and breathe very differently, with their cheeks and mouth.
And in the case of alligators and crocodiles with a through-flow system like that of birds.
14. Reptiles have a 3-chambered heart, except crocodilians which, like mammals, have a 4-chambered heart. Since their hearts cannot pump blood far upwards, reptiles move close to the ground (they 'creep').
Eh? I wouldn't describe a Komodo Dragon as "creeping". But as reptiles don't have a high metabolism they don't need so much oxygen, so they don't need to separate the two halves of the heart (and very little mixing of oxygenated and deoxygenated blood actually goes on thanks to complex valves). Even with their more inefficient hearts reptiles can be pretty active when they want to be.
15. The legs of reptile are splayed out from the body. The legs of mammals are positioned under the body.
Except for dinosaurs (including birds), lots of early crocodiles, modern crocs in a hurry. Oh, and Platypuses and Echidnas. They have a sprawling gait too. But aren't they mammals?
I've actually been trying to work out what kind of creationists the Noah's Ark Zoo people are. They don't seem to accept that the world is 6,000 years old, like AiG do. But they certainly don't like the answer radiometric dating gives. And most bizarre of all is their take on the fossil record- it records the recolonisation of the world after the flood with animals and plants, and as each group became abundant enough to fossilise that's when it turned up in the rock record, despite always having been there. Its a hideous fudge that isn't obviously your typical YEC stuff, and as such means I'm sure these guys are vilified by the AiG crowd. And yet its also at odds with reality. As someone on Pharyngula said "halfway between right and wrong is still wrong".
Oh and that cool new paper on hot-blooded mosasaurs? Your reference is:
Bernard, A. et al. (2010) Regulation of Body Temperature by Some Mesozoic Marine Reptiles. Science, 328, 1379 - 1382
Oh, and you know what really sticks in my craw? The Horniman Museum doesn't have a badge. Bastards.