Pursuant to publishing the post, I received a complaint that I did not properly explain Rabbi Meiselman's view. In this post, I will endeavor to do so more fully. But, as you will see, it merely makes his approach all the more problematic and downright bizarre.
Rabbi Meiselman does not claim that Chazal knew about the platypus per se. They had never been to Australia, nor had they received a vision of a platypus. Rather, he claims that they knew, "from their study of the blueprint of Creation," that there must be an animal, somewhere in the world, which lays eggs and nurses its young. He further seeks to explain why they would call the platypus atalef, which is the name of the bat in the Torah. Rabbi Meiselman explains that just as there is a bird called tinshemes and a sheretz called tinshemes, due to their sharing various characteristics, there is also a "bird" called atalef (the bat) and a quadruped called "atalef" (the platypus), which share significant characteristics. But what are these characteristics by which the platypus earns the same name that the bat earned as an ohf? Rabbi Meiselman first suggests that the platypus, like the bat, has characteristics of both mammals and birds - it is furry, yet possesses a bill and duck-like webbed feet. Alternately, he suggests, the platypus is like the bat in possessing special adaptations for maneuvering in the dark - the bat uses echolocation, and the platypus uses electroreception and mechanoreception (it has tens of thousands of tiny receptive organs on its bill).
That is Rabbi Meiselman's view. I will now present three reasons as to why it is unreasonable in the extreme and does not even assist in removing scientific error from this Gemara. Frankly, I don't really care if he, or anyone else, wants to believe that the atalef of the Gemara is the platypus. The problem is that he is using this in service of his claim that anyone who believes that the Gemara is making an erroneous statement about bats is an unsophisticated heretic.
I. Why Describe the Platypus as an Atalef?
First of all, as discussed at length in the previous post on this topic, if Chazal wanted to tell us about a creature that nobody (including themselves) had seen, the very last thing that they would have done is called it simply by the name of a known animal, the atalef. This is especially true in light of the fact that the term atalef already referred to the bat, which many people mistakenly believe to lay eggs, and would thus assume to be the animal that Chazal were describing.
Rabbi Meiselman seeks to explain why the platypus has significant similarities to the bat that earn it the name atalef. His first way of explaining this is that the platypus is intermediate between mammals and birds in not just one way, but a number of ways. The platypus is furry and nurses its young like other mammals, yet it possesses a bill and duck-like webbed feet as well as laying eggs like birds. Accordingly, the term atalef deservedly refers to the platypus. (In a footnote, Rabbi Meiselman adds that it is "interesting to note" that certain platypus genes resemble those of birds, though he admits that this is not of significance here, since halachah deals only with what can be perceived by the ordinary observer without special equipment.)
But it is very far-fetched to posit that the bat and platypus share the same name due to their both having characteristics of both mammals and birds, when the characteristics of birds that they have are fundamentally different! The platypus cannot fly; instead, it has completely different similarities to birds. Furthermore, webbed feet are not even particularly relevant to birds - some birds possess webbed feet and most do not, just as some mammals (beavers, otters, seals) possess webbed feet and most do not.
Furthermore, the bat's ability to fly is what classifies it in the Torah as a bird. It is what earns its position, not its name (just as the names of the other birds in the list do not reflect their ability to fly). Anything about the name and significance of the atalef would only reflect the ways in which it is different from other birds.
Now let's turn to Rabbi Meiselman's second proposal, that the platypus shares the same name as the bat because atalef is defined as a creature that has (either instead of, or in addition to, intermediate status between mammals and birds) a special adaptation to the dark. In the case of the bat, this is echolocation, and in the case of the platypus, he explains, this is electroreception. But this does not work and is silly for several reasons:
1) The echidna also has electroreceptors (albeit fewer than the platypus), which it uses for locating food in the undergrowth at night. (To this I presume Rabbi Meiselman would respond that it doesn't use them for maneuvering, only for locating food. This would appear to be just another contrivance.)
2) Why on earth would this random feature be a defining characteristic of the atalef? Rabbi Meiselman seeks to make a pattern by noting that the mole, which according to Rashi is also called the atalef, also has adaptations to maneuver in the dark. But aside from this being a view unique to Rashi, Rabbi Meiselman repeatedly states that the Rishonim did not have a clear mesorah regarding zoology and often misinterpreted Chazal's statements because of this. Suddenly Rashi is grounds to create a new definition of the atalef? Rabbi Meiselman himself freely rejected the mole as an atalef in his previous explanation, when he said that the atalef has to have birdlike characteristics!
3) And finally, the clincher. Echolocation and electroreceptors?! Echolocation in bats was only discovered in 1940, using modern scientific technology. Electroreceptors were only detected in the platypus in 1984 by special investigative techniques, 180 years after the platypus was discovered. Rabbi Meiselman himself admits that halachah deals only with what can be perceived by the ordinary observer without special equipment. Indeed, he uses this to claim that Chazal described lice as spontaneously generating for this reason. But he wants to argue that the term atalef is based on echolocation and electroreceptors?! And if we're just talking about an ability to maneuver in the dark - well, there's nothing novel in that, all kinds of nocturnal animals and birds can do that.
In summary, there is no reasonable basis for saying that the platypus should earn the name atalef. And even if there were, Chazal could and should still have referred to it as "another type" of atalef.
II. How Would Chazal Have Known About Such A Creature?
The assumptions being made by Rabbi Meiselman are astounding. Let's make a list of all the things that Rabbi Meiselman claims that Chazal knew "from their study of the blueprint of Creation":
1. The bat is not the only creature which shares characteristics of mammalian and non-mammalian species.
2. Other creatures that share characteristics of both groups, which are thus also called atalef, do so in ways that differ from the bat.
3. In the entire world, there is exactly one creature in this class that has the mammalian/non-mammalian features of milk-secreting and egg-laying.
Note that Rabbi Meiselman gives no explanation whatsoever as to how their study of Torah led to this presumed knowledge. And it's not as though there is a lot of material in the Torah about the atalef to work with. On the other hand, there is an enormous amount of material in the Torah about cosmology, and yet Chazal were not able to figure out that the sun goes on the other side of the world at night rather than behind the sky!
Let us also recall that no Torah scholar before Rabbi Meiselman ever thought that Chazal were talking about anything other than the atalef of the Torah.
III. The Problem with the Echidna
One might think that a person who believes the atalef to refer to the platypus can say that it also refers to both the echidna. But Rabbi Meiselman cannot do this. He does not explicitly say why, but there are several good reasons.
First, in order not to have it look completely lame that Chazal would use the term atalef for the platypus, Rabbi Meiselman has already argued that there are several reasons for using this term. The reasons that he gives (a beak, webbed feet) do not apply to the echidna.
Second, the platypus and the echidna are very different animals. The platypus is a mostly aquatic animal that resembles a beaver. The echidna is terrestrial and looks like a porcupine. One cannot claim that two such different animals are the same min.
There is a third reason why it is problematic to say that the term atalef includes both the platypus and the echidna. If any creature can be called an atalef merely because it lays eggs and nurses its young, then the Gemara's entire rule becomes meaningless. Remember, too, that according to Rabbi Meiselman, Chazal did not know specifically about the platypus and echidna; thus there could be any number and variety of egg-laying lactating animals in the world. The Gemara said that there is a lone exception to the principle that "every egg-laying animal does not nurse its young" - but if atalef can include any number and variety of animals that are an exception to this rule, then the Gemara is merely saying that "every egg-laying animal does not nurse its young, except for all those that do," which would make no sense.
Thus, Rabbi Meiselman, by arguing that the atalef is a term that is well suited to the platypus, and thereby made the description of the atalef correct, has simply forced a different error into the Gemara's rule.
Again, I must stress that I don't really care less if Rabbi Meiselman, or anyone else, wants to believe that the atalef of the Gemara is the platypus. The problem is that he is using this in service of his claim that anyone who believes that the Gemara is making an erroneous statement about bats is an unsophisticated heretic.