[00:00.00]NARRATOR: Listen to part of a lecture in a zoology class.
[00:04.40]FEMALE PROFESSOR: OK, we’ve been talking about birds, modern birds, and their environments. [00:09.19]But it might be interesting to say something about ancient birds, especially the one called archaeopteryx.
[00:15.47]Difficult word, I know. But all it means is “ancient wing.” [00:20.42]Uh, the first “archaeopteryx” was discovered in 1861, fossilized in a piece of stone from a quarry in Germany. [00:28.35]From a paleontologist’s point of view, this was a real stroke of luck. [00:32.93]Uh, not only were the fragile bones of this ancient bird extremely well-preserved—and that’s pretty rare for a bird—which is why we don’t find very many of them in the fossil record, but the fine details of this fossil were really quite extraordinary—you could even detect impressions of the feathers on it. Amazing, huh? Yes, Mike?
[00:53.37]MALE STUDENT: Why was it that details like that showed up in this particular fossil?
[00:57.65]FEMALE PROFESSOR: Well, I mentioned before that the archaeopteryx fossil was found in a quarry– you know, where people cut stone– in this case, exceptionally fine-grained limestone. [01:07.84]And the point is… the particles that this limestone was made of were so fine that the limestone preserved much of the fossil in exquisite detail, and, as I said, revealed impressions of details even as small as the lines in a feather.
[01:21.92]But that’s pretty rare. There are not many fossils of ancient birds in general, being so fragile, much less archaeopteryx fossils. [01:30.78]So we don’t know for sure as much as we’d like to, but there are lots of opinions. It’s like, say, the Mona Lisa… you guys have seen copies of that painting, right? The Mona Lisa? [01:42.37]Well, one of the great things about it is that each person who sees that painting understands it a little differently, according to their own biases. [01:50.03]You might say that the archaeopteryx is a scientific Mona Lisa.
[01:54.96]MALE STUDENT: How so?
[01:56.04]FEMALE PROFESSOR: Oh… well, ornithologists, who study modern birds, tend to see the archaeopteryx as an early ancestor of the birds we see today. [02:04.51]But paleontologists, the ones who study fossils and forms of ancient life, point out its similarity to some dinosaur species. [02:13.02]I mean, it is very different from modern birds in some important ways—there’s no beak, the tail is long and bony the way a reptile’s is, rather than short and stubby like a modern bird’s. [02:24.34]And it has claws at the ends of what are called its wing fingers … they’re generally absent in modern birds.
[02:30.72]FEMALE STUDENT: So ornithologists think it’s a bird, and paleontologists say it isn’t?
[02:35.72]FEMALE PROFESSOR: Did I say that? No … no … I’m sorry, that’s not what the debate’s about. [02:40.86]The archaeopteryx had feathers, and creatures with feathers are classified as birds.
[02:45.98]FEMALE STUDENT: So … then … what is the debate about?
[02:49.52]FEMALE PROFESSOR: OK. Well, like I said, even with the lack of a beak, and with its tail and claws, it’s still classified as a bird. [02:58.09]The debate is ... well, evolutionarily speaking, where does archaeopteryx fit? [03:04.37]For the paleontologist who studies other dinosaurs of that period, it’s, well, in a lot of ways, nothing all that unusual ...
[03:12.43]MALE STUDENT: Except for the feathers …
[03:14.14]FEMALE PROFESSOR: Except for the feathers, exactly. [03:16.84]Paleontologists see the archaeopteryx in terms of its wider evolutionary relationships … um, they see it as a kind of link, almost, between dinosaurs and modern birds, or at least closely related to one. [03:29.74]And for the ornithologists, the archaeopteryx is a bird with exceptional features, and the earliest bird on record. [03:37.16]A basic belief of ornithologists is that birds evolved … uh, that their evolution is closely related to their developing the ability to fly. [03:46.95]But some of those features I mentioned earlier—the lack of a bird-like tail, the claws—these don’t do much to support the notion that the archaeopteryx could fly. [03:57.72]But then again, it did have other modern bird-like features, so it probably could rise up off the ground, but only very awkwardly, and it probably wasn’t too graceful once it got into the air. [04:10.64]Actually, though, as to whether the archaeopteryx could fly, we don’t really have conclusive evidence one way or the other.
[04:17.87]MALE STUDENT: So do you agree with the paleontologists, professor, or the ornithologists?
[04:23.24]FEMALE PROFESSOR: Well, the most recent research is based on some fossils being found in China. [04:28.78]It’s hardly complete, but I find its conclusions really compelling. [04:33.81]Uh, apparently, the feathers of the archaeopteryx may have evolved not for flight, but either for display … um, males using colorful feathers to attract a mate … or for insulation. [04:46.17]And, feathers are very useful for conserving body heat in cold temperatures.
托福14天冲刺微信战团