This is an important new fossil, a 47 million year old primate nicknamed Ida. She’s a female juvenile who was probably caught in a toxic gas cloud from a volcanic lake, and her body settled into the soft sediments of the lake, where she was buried undisturbed.

What’s so cool about it?

Age. It’s 47 million years old. That’s interestingly old…it puts us deep into the primate family tree.

Preservation. This is an awesome fossil: it’s almost perfectly complete, with all the bones in place, preserved in its death posture. There is a halo of darkly stained material around it; this is a remnant of the flesh and fur that rotted in place, and allows us to see a rough outline of the body and make estimates of muscle size. Furthermore, the guts and stomach contents are preserved. Ida’s last meal was fruit and leaves, in case you wanted to know.

Life stage. Ida is a young juvenile, estimate to be right on the transition from requiring parental care to independent living. That means she has a mix of baby teeth and adult teeth — she’s a two-fer, giving us information about both.

Phylogeny. A cladistic analysis of the fossil revealed another interesting point. There are two broad groups of primates: the strepsirrhines, which includes the lemurs and lorises, and the haplorhines, which includes monkeys and apes…and us, of course. Ida’s anatomy places her in the haplorhines with us, but at the same time she’s primitive. This is an animal caught shortly after a major branch point in primate evolutionary history.

She’s beautiful and interesting and important, but I do have to take exception to the surprisingly frantic news coverage I’m seeing. She’s being called the “missing link in human evolution”, which is annoying. The whole “missing link” category is a bit of journalistic trumpery: almost every fossil could be called a link, and it feeds the simplistic notion that there could be a single definitive bridge between ancient and modern species. There isn’t: there is the slow shift of whole populations which can branch and diverge. It’s also inappropriate to tag this discovery to human evolution. She’s 47 million years old; she’s also a missing link in chimp evolution, or rhesus monkey evolution. She’s got wider significance than just her relationship to our narrow line.

People have been using remarkable hyperbole when discussing Darwinius. She’s going to affect paleontology “like an asteroid falling down to earth”; she’s the “Mona Lisa” of fossils; she answers all of Darwin’s questions about transitional fossils; she’s “something that the world has never seen before”; “a revolutionary scientific find that will change everything”. Well, OK. I was impressed enough that I immediately made Ida my desktop wallpaper, so I’m not trying to diminish the importance of the find. But let’s not forget that there are lots of transitional forms found all the time. She’s unique as a representative of a new species, but she isn’t at all unique as a representative of the complex history of life on earth.

When Laelaps says, “I have the feeling that this fossil, while spectacular, is being oversold,” I think he’s being spectacularly understated. Wilkins also knocks down the whole “missing link” label. The hype is bad news, not because Ida is unimportant, but because it detracts from the larger body of the fossil record — I doubt that the media will be able to muster as much excitement from whatever new fossil gets published in Nature or Science next week, no matter how significant it may be.

Go ahead and be excited by this find, I know I am. Just remember to be excited tomorrow and the day after and the day after that, because this is perfectly normal science, and it will go on.

Laelaps has some serious reservations about the analysis — the authors may not have done as solid a cladistic analysis as they should, and its position in the family tree may not be as clear as it has been made out to be.

Franzen JL, Gingerich PD, Habersetzer J, Hurum JH, von Koenigswald W, Smith BH (2009) Complete Primate Skeleton from the Middle Eocene of Messel in Germany: Morphology and Paleobiology. PLoS ONE 4(5): e5723. doi:10.1371/journal.pone.0005723.

Isn’t that beautiful? It’s an ancient footprint in some lumpy rocks in Kenya…but it is 1½ million years old. It comes from the Koobi Fora formation, familiar to anyone who follows human evolution, and is probably from Homo ergaster. There aren’t a lot of them; one series of three hominin trails containing 2-7 prints, and a stratigraphically separate section with one trail of 2 prints and an isolated single print. But there they are, a preserved record of a trivial event — a few of our remote relatives taking a walk across a mudflat by a river — rendered awesome by their rarity and the magnitude of the time separating us.

Here’s one of the trails:

(Click for larger image)
Tessellated swath of optical laser scans of the main footprint trail on the upper footprint surface at FwJj14E. Color is rendered with 5-mm isopleths.

It’s an interesting bridge across time. There they were, a couple of pre-humans out for a stroll, perhaps on their way to find something for lunch, or strolling off to urinate, probably nothing dramatic, and these few footprints were left in drying mud to be found over a million years later, when they would be scanned with a laser, digitized, and analyzed with sophisticated software, and then uploaded to a digital network where everyone in the world can take a look at them. Something so ephemeral can be translated across incomprehensible ages…I don’t know about you, but I’m wondering about the possible future fate of the debris of my life that has ended up in landfills, or the other small smudges across the landscape that I’ve left behind me.

And what have we learned? The analysis has looked at the shape of the foot, the angle of the big toe, the distribution of weight as the hominins walked across the substrate, all the anatomical and physiological details that can be possibly extracted from a few footprints.

(Click for larger image)
Optical laser scan images color-rendered with 5-mm isopleths for footprints at both FwJj14E and GaJi10. (A) Isolated left foot (FUI1) on the upper footprint surface at FwJj14E. (B) Photograph of FUI8 on the upper footprint surface at FwJj14E, showing good definition of the toe pads; the second toe is partially obscured by the third toe. (C) Second trail on the upper footprint surface at FwJj14E, showing two left feet. (D) Third trail on the upper footprint surface at FwJj14E, showing a right and a left foot. (E) Print R3 from GaJi10 (22), re-excavated and scanned as part of this investigation. (F) Partial print (FUT1-2) on the upper footprint surface at FwJj14E; the heel area has been removed by a later bovid print. (G) Print FLI1 on the lower footprint surface at FwJj14E, rendered with 5-mm alternating black and white isopleths. (H) Inverted image of the toe area of print FUT1-1 with alternating 5-mm black and white isopleths. Note the locations of the pads of the small toes and the presence of a well-defined ball beneath the hallucial metatarsophalangeal joint. The first, third, and fifth toes are marked D1, D3, and D5, respectively.

The answer is that these beings walked just like us. The tracks are noticeably different from the even older footprints of australopithecines found at Laetoli, from 3.5 million years ago. The foot shape and the stride of Homo ergaster was statistically indistinguishable from those of modern humans, even though we know from the bones associated with these species that they were cranially distinct from us. This is not a surprise; it’s been known for a long time that we evolved these bipedal forms long ago, and that the cerebral innovations we regard as so characteristic of humanity are a relative late-comer in our history.

Remember, though, these are 1½ million years old, 250 times older than the age of the earth, according to creationists. That’s a lot of wonder and history and evidence to throw away, but they do it anyway.

Bennet MR, Harris JWK, Richmond BG, Braun DR, Mbua E, Kiura P, Olago D, Kibunjia M, Omuombo C, Behrensmeyer AK, Huddart D, Gonzalez S (2009) Early Hominin Foot Morphology Based on 1.5-Million-Year-Old Footprints from Ileret, Kenya. Science 323(5918):1197-1201.