davegodfrey: South Park Me. (Default)
I keep fish. Until today I had three weather loaches, Sixteen White Cloud Mountain Minnows, and a male and two female American-Flag Fish. So called because the males look like the American Flag. They're mostly vegetarian, and the males especially, are renowned for being belligerent arseholes. Compatible tankmates should be "robust enough to survive or fast enough to escape" They get to two-and-a-half inches long (the females are a little smaller). And they look like this:

I say, until today, because today I found "Mr Grumpy" tangled up in some thread I'd used to attach moss to a piece of wood. The thread had been wrapped around the wood, and a piece of rootlet, and he'd got in between it, probably to munch on a bit of algae (Like most fish they're perpetually hungry, but apparently are a little calmer if they've got something to snack on throughout the day. The stereotypes just keep building up don't they? Its most unfair) he'd got trapped, and suffocated.


Mr Grumpy. c2010- 7th November 2011. Leaves behind two female companions, but no children.
davegodfrey: South Park Me. (Default)
I have two fishtanks. One's a big community one with interesting subtropicals like the very personable Weather Loach (Misgurnus anguillicaudatus, the very pretty White Cloud Mountain Minnows (Tanichthys albonubes) and the mildly psychotic American-Flag Fish (Jordanella floridae).

I also have a smaller 40cm cube with more red cherry shrimp than the mind can comfortably entertain. There's also a small group of the utterly stunning Pacific Blue Eye (Pseudomugil gertrudae). Sadly the blue-eyes haven't done terribly well, from having 8 I'm now down to four, and while I've seen the males sparring with each other and flashing their fins at the females I've seen no sign of spawning. I think they'd probably do better in a larger group and with a bigger tank. I've decided not to replace the ones I have when they shuffle off this mortal coil- I've had something like 18 Rosy Bitterlings in the past year, and I'm down to my last female. If I can't keep the fish alive I think its best not to try until I have rather more experience. Besides as a beginner with a first aquarium, trying to keep a fish that breeds in Swan Mussels (which are renowned as impossible to keep alive) was perhaps rather too ambitious, though I did see lots of mating dances and one somewhat abortive spawning, so I was well pleased with the result. I'll definitely come back to the Blue-Eyes.

So I added three Least Killifish (Heterandria formosa one of which promptly died during quarantine, and a second jumped out the tank. Today I've seen two babies! There's no sign of mother however- she may well be hiding in the foliage (its rather densely planted), although both babies were relatively large, so they may have been in the tank for some time.

I think I shall have to track down a few more- unfortunately they seem rather thin on the ground only one place in London seems to have them, while others have stocked them they only crop up in small batches, and "when they're gone, they're gone".
davegodfrey: Coelacanth (Science)
So  having had a look at the paper, and watched the video courtesy of Nature I thought I'd see how the various newspapers reported this new and interesting discovery.

As far as I can see The Daily Express doesn't cover it at all. But as their astrologer is writing a guide to getting fit in 2010 I think they might have given up on being a newspaper these days.

The Mail throws the "Missing Link" phrase around in the first paragraph. Which is a shame, because I've not seen it mentioned anywhere in the reporting or the press release. If anything this is something that would have been largely ignored if it was contemporaneous with the body fossils- "Oh neat, tetrapod trackways. Oh they're marine. That's interesting, virtually everything else is freshwater" would have been the response. However the rest of the article is not bad- the quote from Ahlberg reads like the abstract, and they've lifted some quotes from Phillipe Janvier's "News and Views" article accompanying the Nature paper. I think they fumbled it a bit, but made a decent recovery. Just don't look at the comments.

The Guardian is pretty good actually. Doesn't use the "missing link" phrase, which I think is a win. Quotes Janvier (who made the important point that the sequence of fossils probably hasn't changed, its just that the timing of the actual transition is way off). It also quotes Ahlberg and Jenny Clack (though it initially spelt her name wrong- but this is the Guardian, so that's to be expected). Where I think it does best is online, where there's the blog by Adam Rutherford providing more information I mentioned last time.

The Indy is generally very good, and provides more information about the circumstances leading up to the find- they were thought to be dinosaurs until they had another look at the fossils in the surrounding rocks to work out how old they really were. It probably explains why the article says "They occurred in a rock formation several metres beneath a younger rock formation." because otherwise that's a totally pointless statement- there's no information about why this younger formation is important. Did it contain the conodonts that they used to work out how old the rocks were? Was it just a pretty colour? What? Enquiring minds wish to know.

The Times however seems to be making stuff up. It describes the creature that made the tracks as looking like a stout crocodile, which is not an inaccurate description of the typical early tetrapod. However it says that; "However, unlike the modern-day crocodile, the ancient creature appears to have held its body up from the ground as there is no trace of it being dragged along. It may have been closer to a dog in terms of posture." No. Seriously. Just No. Crocs have legs that stick out from the side less than that of lizards or salamanders, giving them a semi-erect gait that raises their bodies off the ground. Dogs have a very different gait, their legs are directly under their bodies like dinosaurs, and mammals. All the early tetrapods have sprawling gaits- we don't see body or tail trails because the animal was supported by water in the intertidal zone, and because it had a sacrum which allowed it to support its tail with the hind limbs. Dogs don't enter into this anywhere.

Its also not true that the rocks "teemed with marine fossils". Tracks are common, but body fossils are extremely rare, and this is not uncommon. There seems to be something about environments that are good for preserving tracks, but lousy for preserving the organisms that made them. I think however they may have redeemed themselves by solving the question of why they were thought to be dinosaur tracks- the man who first discovered them didn't know how old the rocks were.

The red-tops seem to have completely ignored it, which is not surprising- Metro gave it a sentence or two, and I can't find it on the intertubes.

So not a bad showing for the papers this time round. Shame the creationists turn up with their "how can you know so much from a footprint?" crap. Well dear, lots. There's a whole science out there that you're completely ignorant of called ichnology.
davegodfrey: Coelacanth (Science)
The following is adapted from a dissertation I wrote several years ago.

Fossils have been recognised as the remains of living organisms since the time of Leonardo da Vinci and before. At the close of the 18th century the French anatomist George Cuvier developed the idea of extinction, demonstrating that many fossils are not those of modern species. Erasmus Darwin and Jean Baptiste Lamarck formulated some of the first ideas suggesting that species were not immutable. At the same time James Hutton was formulating his theory of the earth, and demonstrated that the earth was much older than the ages biblical chronologies allowed (Bowler 1989). These three ideas were to become important questions and discussed much through the following century.

A (very) brief history of collecting )

Agassiz (1835) described osteostracean remains in his works on fossil fishes, creating the genus Cephalaspis for four species, C. lyelli, C. lewisii, C. lloydii, and C. rostrata. These species were not initially recognised as jawless. Of these four, Thomas Henry Huxley restricted Cephalaspis to C. lyelli, and created the genus Pteraspis for Agassiz’s other species in the genus (Huxley 1858). E. Ray Lankester separated heterostraceans and osteostraceans into separate groups in his 1868 monograph.

Ostracoderms. Some of the best fish ever... )

Revolutions in science are not instantaneous. New theories and ways of thinking take time to spread and gain respectability. The paradigms influencing the work of the second period, the work of Cope, William Patten, and others are the result of the publication of Charles Darwin’s Origin of Species in 1859, thirty years before, and the successful spread of evolutionary thinking in the latter half of the 19th century. Similarly, while Løvtrup produced one of the first cladograms of modern vertebrates in 1977, the cladistic method began with the entomologist Willi Hennig’s influential 1969 book Insect Phylogenetics where the principles of cladistics were first established.

References. )
davegodfrey: South Park Me. (Default)
Up until now flatfish have been been a bit of a problem. They're very weird, going through a metamorphosis so that both eyes end up on the same side of the head. The patterns of development are well understood, (though not at a genetic level) but their early evolution is not well understood. The lack of intermediate fossils has lead to workers such as Goldschmidt proposing "hopeful monsters" and others, like St. George Jackson Mivart doubting natural selection.

However Matt Friedman, a doctoral student in Chicago, has found the first fossils illustrating this change. Matt found the fossils in a drawer of indeterminate fish remains in Vienna, and re-examined two species of a similar genus Amphistium. Matt Freidman prepared the rediscovered specimen, recognised it as a new genus and species, Heteronectes chaneti, and has a paper in Nature for his trouble.

The three species show incomplete migration of the eyes, having one on each side of the head, but displaced, and the skulls are clearly asymmetric, rather than distorted during fossilisation as had been thought. Another fact indicating the primitive nature of these fishes is that Amphistium is known from several specimens, and they are both left and right-handed, a character seen in the primitive living Psettodes (Spiny Turbots), but not in the more derived forms.

Another feature from the point of view of evolution is that these animals were clearly successful predators, as stomach contents are known from one specimen, so the intermediate condition was clearly not maladaptive as creationists like to suggest these things are.

Incidentally Friedman seems to be making a career out of re-examining neglected and ignored specimens. I met him at SVPCA last year, when he presented a talk on the "Cretaceous Swordfish" "Protosphyraena" gladius, which turns out not to be a Protosphyraena at all, but a something else entirely, and is closely related to the giant filter-feeder Leedsichthys.
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davegodfrey: South Park Me. (Default)
The Evil Atheist Your Mother Warned You About

November 2013

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