Octopus cyanea
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
This has got to hurt.
That’s a yellow shafted northern flicker on the left, and a redheaded woodpecker on the right…and the flicker has got its claws on the woodpecker’s tongue. I call foul!
In a potentially exciting development, researchers have announced the completion of a rough draft of the Neandertal genome in a talk at the AAAS, and in a press conference, and the latest issue of Science has a number of news articles on the subject. And that is a reason for having some reservations. There is no paper yet, and science by press release raises my hackles, and has done so ever since the cold fusion debacle. Not that I think this is a hoax or error by any means, but it’s not a good way to present a scientific observation.
Also, the work has some major limitations right now. They’ve got about 60% of the genome so far, and it’s all entirely from one specimen. From the age of these bones, degradation is inevitable, so there are almost certainly corrupted sequences in there — more coverage would give me much more confidence.
With those caveats, though, there are some tantalizing hints, and the subject is so exciting that it’s understandable why there’d be rush to announce. So far, they’ve identified approximately 1000-2000 amino acid differences in the coding part of the genome (human-chimp differences are about 50,000 amino acids), but there’s no report of any detectable regulatory differences.
I’m withholding judgement until I see a real paper; for now, you have to settle for a podcast with a science journalist, which just isn’t meaty enough yet.
Fans of the great Cambrian predator, Anomalocaris, will be pleased to hear that a cousin lived at least until the Devonian, over 100 million years later. That makes this a fairly successful clade of great-appendage arthropods — a group characterized by a pair of very large and often spiky manipulatory/feeding arms located in front of the mouth. Here’s the new fellow, Schinderhannes bartelsi:
There are some significant differences between familiar old Anomalocaris and Schinderhannes. Anomalocaris was a monster that grew to about a meter long; this little guy is about a tenth of that, around 4 inches. He also has those interesting “wings” behind his head, which presumably aided in swimming.
Another significant feature of this animal is that it has characters that place it in the Euarthropoda, which makes great appendages paraphyletic and primitively present in euarthropods. Those great appendages have long been a curiousity, and we’ve wondered whether they are a unique innovation that was completely lost in modern arthropods, or whether they evolved into one of the other more familiar cephalic appendages; the authors suggest that this linkage with the euarthropod family tree implies that chelicera (what you may recognize as the big paired ‘fangs’ of spiders) are modified great appendages.
Kühl G, Briggs DEG, Rust J (2009) A Great-Appendage Arthropod with a Radial Mouth from the Lower Devonian Hunsrück Slate, Germany. Science 323(5915):771-773.
Just wait — this one will be featured in some cheesy Sci-Fi channel creature feature in a few months. Paleontologists have dug up a fossil boa that lived 58-60 million years ago. They haven’t found a complete skeleton, but there’s enough to get an estimate of the size. Look at these vertebrae!
Just to put it in perspective, the small pale blob between a and b in the photo above is an equivalent vertebra from an extant boa, which was 3.4 meters long. The extinct beast is estimated to have been about 13 meters long, weighing over 1100 kg (for us Americans, that’s 42 feet and 2500 pounds). This is a very big snake, the largest ever found.
The authors used the size of this snake to estimate the temperature of this region of South America 60 million years ago. Snakes are poikilotherms, depending on external sources of heat to maintain a given level of metabolic activity, and so available temperature means are limiting factors on how large they can grow. By comparing this animal’s size to that of modern tropical snakes, and extrapolating from a measured curve of size to mean annual temperature, they were able to calculate that the average ambient temperature was 30-34°C (American cluestick: about 90°F); less than that, and this snake would have died.
From other data, they know that the atmospheric CO2 concentration at this time was about 2000 parts per million, and that the forests it lived in were thick, wet, and rainy. They also estimate that slightly later, about 56 million years ago, mean tropical temperatures would have soared to 38-40°C (102°F), and would have killed off many species.
So there you go…this is one place I think I’d avoid if I had a time machine. It was a thick-aired, muggy, sweltering oven, with giant snakes crawling about. They were likely to have eaten large crocodilians, so I suspect a time-traveling human would be nothing but a quick hors d’ouevre. They’re still interesting, though, especially as an example of evolution and climate science meeting in a mutually revealing fashion.
Head JJ, Block JI, Hastings AK, Bourque JR, Cadena EA, Herrera FA, Polly D, Jaramillo CA (2009) Giant boid snake from the Palaeocene neotropics
reveals hotter past equatorial temperatures. Nature 457(7230):715-718.
My teaching schedule this semester is a major time-suck; I’m teaching genetics and all of its associated labs (you really don’t want to know how much prep time goes into setting up fly labs), I’m doing some major revision of the content this year, and I’ve got this asymmetric schedule that packs everything into the first half of each week. So I simply have to protest when those evil (Stein was right!) scientists announce a major discovery on a Tuesday, which just happens to be the very worst day of the week for me. They’ve gone and found another important whale transitional fossil, Maiacetus, and I’m just going to have to tell you to go read a bunch of other fine blogs that already have it covered.
(A, B)- Dorudon atrox (5.0 m; 36.5 Ma) based on UM 101222 and 101215 [11] in lateral and dorsal views, respectively. (C, D)- Maiacetus inuus (2.6 m; 47.5 Ma) based on male specimen GSP-UM 3551 in lateral and dorsal views, respectively.
It’s beautiful. It’s clearly adapted for aquatic life, but it has another revealing feature: this specimen was pregnant at death, and the fetus is oriented for a head-first birth, which is not good for birth at sea (the head would pop out, baby would take its first breath, and drown before the tail emerged), so this animal would have had to give birth on land.
But like I said, you’ll have to read Carl Zimmer, Ed Yong, Brian Switek, or Greg Laden this time around for all the details. Or read the paper yourself! It’s freely accessible.
You’ve got to be impressed with the cephalopod-butchering skills of this dolphin. Especially be sure to check out the gallery of grisly photos.
I know, I like cephalopods. But I eat them, too!
