These monsters are all dead

I hope you all like long tubular creatures, because that’s all I’ve got for you today. Maybe they’d be less horrifying if they had lots of legs?

Here’s a 4-meter long salamander-like beast from the Permian, named Gaiasia.

I’ve seen giant salamanders before, but not ones with big box-like skulls full of razor-sharp fangs.

Here’s another muscular tube, Vasuki indicus, only 47 million years old, but somewhere around 10-15 meters long.

The amusing thing about this beast is that everyone in the popular press treatment is making it all about how long it is — it’s a partial skeleton, there’s not enough to determine exactly how long it is. It’s either shorter than Titanoboa, the gold standard of giant ancient snakes, or bigger than Titanoboa. It’s not a competition, people! They’re separated by about 10 million years. But of course they’re in competition for starring roles in cheesy sci-fi CGI epics.

That’s why we’re seeing ridiculous comparisons like this one:

OK, the snake was longer than T. rex, but so what? It wasn’t as massive, and they were temporally distant from one another. This illustration reveals how some people are thinking:

That could be an ad for the next movie by The Asylum. These kinds of team-ups are popular to promote cheese, like Godzilla vs. Mechagodzilla or Dracula vs. Frankenstein. Learn to love Vasuki for itself, OK?

A Carboniferous arachnid

This week has been a good one for chelicerate evolution. Here’s another fossil, Douglassarachne acanthopoda, which was creeping around in the forests of Illinois in the late Carboniferous.

Douglassarachne acanthopoda n. gen. n. sp., holotype and only known specimen FMNH PE 91366; for interpretative drawings and scale, see Figure 2. (1) Part, detail of distal femur and more-distal podomeres, showing nature of curved macrospines on lateral edge of distal podomeres, bases of macrospines on dorsal surface of femur; (2) counterpart, detail of posterior opisthosoma showing bilobed structure at base of anal tubercle.

What is it? I don’t know. The authors are unsure. It’s an arachnid, but it could be in the spider lineage or the harvestman lineage, or it could be its own weird thing. It’s spiderish, anyway.

Douglassarachne acanthopoda n. gen. n. sp., reconstruction of the possible appearance of the animal in life.

An Ordovician ancestor to spiders

On this Memorial Day, I’m going to have to have a discussion with my spiders about their distinguished, noble ancestry. It was kind of Nature to publish a study of their many-times-great grand uncles, an ancient euchelicerate named Setapedites abundantis, a common fossil found in Moroccan sediments that are about 478 million years old, which puts it right in the middle of the Great Ordovician Biodiversification Event, a key moment in the evolution of modern taxa.

This is not a spider, though. It belongs in the euchelicerata, the large systematic group that includes spiders, scorpions, ticks, horseshoe crabs, sea scorpions, and other extinct groups. As you might guess from the name, a key feature is the presence of chelicerae, anterior appendages that in spiders carry the venomous fangs. It also has a common feature we see in both spiders and horseshoe crabs, the fusion of the anterior segments to form a prosoma, with posterior segments forming the abdomen or opisthosoma.

While it’s a cool looking little dude, it’s marine and pretty remote from modern chelicerates. From the dorsal side, it looks like an undistinguished little crustacean, of a type that was probably swarming in Ordovician seas.

A, B MGL.102899 and interpretative drawing, articulated specimen in dorsal view. C, D MGL.102828 and interpretative drawing, articulated specimen in dorsal view. E, F MGL. 102872 and interpretative drawing, articulated specimen in dorsal view. Abbreviations: btg, bipartite tergites; mr, median ridge; pl, pleura; pr, prosomal rim; saxn, sub-axial node; sr, sunken region; t1–11, tergites 1–11; t, telson; tk, telson keel. Scale bars, (A–F) 1 mm.

Where it gets interesting is when it’s flipped over, and you get a glimpse of the mass of limbs.

A, B YPM IP 517932c and interpretative drawing (counterpart), articulated specimen in ventral view. C, D YPM IP 517932c and interpretative drawing, chelicerae, and labrum anatomy detail. E, F Close-up of the prosoma of MGL.102934 and interpretative drawing, in dorso-lateral view. G, H Close-up of the prosoma of MGL.102634 and interpretative drawing, in ventral view. I, J Close-up of the prosoma of MGL.102800a under alcohol and polarized lighting, and interpretative drawing, in ventral view. Abbreviations: 1–6, podomeres 1–6 of the exopod; ptp, pretelsonic process; bs, basipodite; bst, brush-like setae; che, chelate podomere; db, doublure; lb, labrum; ss, single setae; st, pair of setae. Chelicerae are highlighted in gray, endopods in blue, exopods in green, opisthosomal appendages in red, and the pretelsonic process in purple. Scale bars, (A, B) 1 mm; (C, D) 100 µm; (E–K) 500 µm.

In front of the jaws proper (labrum, lb) it has a pair of small chelicerae (che). These have since evolved into the massive, sharptoothed chompers you can see my tarantula using to turn a mealworm into macerated mush.

Setapedites wasn’t such a fierce predator. Here’s what it looked like.

Illustration by Elissa Sorojsrisom.

Cute, right? I don’t know why it’s drawn as a swimmer, though — with that anatomy, it looks more like a benthic organism.

The final bit of interesting information is that they mapped out the correspondences in the segmentation of this animal with other, similar fossils and the extant Xiphosurians.

Simplified extended majority rule tree of a Bayesian analysis chronogram of euchelicerate relationships, based on a matrix of 39 taxa and 114 discrete characters, showing the position of Setapedites abundantis within Offacolidae. Lineages extending after the Silurian are indicated with arrowheads. Schematic models of the body organization in Habelia, Setapedites abundantis, Dibasterium, Offacolus, and Xiphosurida illustrate the origin and early evolution of euchelicerate uniramous prosomal appendages and tagmosis. Roman numbers designate somites. Prosoma somites are highlighted in blue, pre-abdomen somites in yellow, abdomen somites in brown, and the possible anal pouch or post-ventral structure (pvs) in purple. Black dorsal lines indicate tergites and cephalotorax. Schematic model of Xiphosurida Offacolus, and Dibasterium from 45, Habelia

Also of note: Setapedites had biramous appendages, a feature that is mostly kind of lost in modern arthropods — the outer branch got adapted into gills and lungs and even wings.

I can’t help but notice that domestication and artificial selection turns wolves in little yapping Pomeranians, but natural selection turns shrimp into tarantulas.

Burying the dead

If you have a subscription to Netflix, you might want to watch Unknown: Cave of Bones, about the discovery of Homo naledi in the Rising Star cave system. It’s spectacular.

On the other hand, if you’re claustrophobic, you might want to skip it. I’m not particularly, but I watched the video of those women wriggling their way down a narrow crack to reach the Dinaledi Chamber gave me a rising sense of panic. There’s no way I could put myself in that position without having a screaming heebie-jeebie fit.

If you can get past that, though, it’s worth it to watch the adventure of science.

First feathers, now lips?

OK, guys, this has gone far enough. I grew up on images of dinosaurs that portrayed T. rex as hulking, scaly, snaggle-toothed dinosaurs, stomping through jungles and roaring. Now look at this…this…revisionism.

Theropod dinosaurs such as the iconic Tyrannosaurus rex have long been portrayed with their teeth fully visible, similar to extant crocodilians. This pattern of portrayal largely had to do with relatedness between dinosaurs and crocodilians and the relationship between tooth and jaw size. Cullen et al. tested hypothesized facial reconstruction in this group using histological analysis of tooth wear patterns and quantitative relationships between skull length and tooth size in both extinct and extant reptiles. Contrary to depictions that have dominated for more than a century, they found that theropods, including T. rex, had lips that covered their teeth, leaving them looking more like modern Komodo dragons than crocodiles.

Apparently, they covered up their dagger-like teeth behind lips, like perfect gentlemen.

Comparisons of the reconstructions of T. rex. (A) Skull, based on Field Museum of Natural History specimen FMNH PR 2081. (B to E) Two hypothetical flesh reconstructions, one with exposed teeth (B) and an associated cross section of the snout (C) and one with extraoral tissues covering the teeth (D) and an associated cross section of the snout (E).

I tell you, if some smarty-pants does an analysis next that shows that T. rex had a lovely singing voice and went “tweet tweet,” I’m going to turn this thing around and cancel the time machine project. There’ll be no point.

What an odd little beastie

I never heard of the Thylacocephala until I saw this video, and they are bizarre arthropods, now extinct, unfortunately. I learned something new!

At first I thought these were some strange planktonic creatures, but they were 20-30cm long. They were actively swimming predators that looked like some kind of remote drone submersible. They thrived from the Ordovician to the upper Cretaceous, making it kind of ridiculous that I knew nothing about them until now.

Vulcanized fossil spiders

And they fluoresce, too!

Part and counterpart of two fossil spiders shown in plain light and under UV illumination.

These are part of a well-known invertebrate fossil bed, 22.5 million years old, in France. It contains lots of well preserved insects and spiders, and one question is…why? What makes this particular place so good at preserving these delicate specimens?

The fluorescence was a clue. They dug into the chemistry of the fossils, and figured out that the glow was produced by the sulfurization of chitin, that as the dead spiders sank in the diatom-rich waters of an ancient pond, the sulfur in the diatoms reacted with the chitin carbohydrate to produce a tough carbon polymer, inedible to the microbes, that could last for millions of years.

Cartoon shows the entire proposed pathway: spider becomes entrained in planktonic diatom mat. Pieces of the diatom mat, both with and without spiders entrained within fall to the sediment floor against a background sedimentation of other diatoms and algae (gray dots). With time, these sediments become compressed and preserved into the rock record. a Chemical composition of chitin. Two chains of chitin are illustrated, organized in anti-parallel. Gray boxes indicate the carbonyl functionalities on the chitin. b Sulfonate-containing molecule, which are common in diatom EPS, can undergo microbial sulfate reduction (MSR), leading to the production of sulfide. c Chitin molecule after sulfurization. C–S bonds could potentially replace the carbonyl functionalities, and S–S bridges could form across the chitin chains. d Idealized molecule representing a chitin polymer after further diagenetic alteration, which could result in the formation of aromatized carbon.

I thought that was kind of neat. It’s also a reminder to biology students that you never know where that organic chemistry we make you take might be useful.

I could be worse

I know many of my readers shudder in dread whenever I mention “sp*d*rs”, but just imagine if Arthropleura hadn’t died off a few hundred million years ago — I’d be growing them in my lab right now and posting photos of my cuties for you to see. This is in the news now because they just found a third fossil.

Sadly, not only have only a few of these humongous millipedes been found, but they’re all fragmentary. All we have are chunks — chunks that are several feet long — of the beast. Nobody has yet found a fossilized Arthropleura head. Just imagine all the eyes, and the nasty great mandibles, and the hungry expression on their face, if you can figure out the various bits of what passes for a face in a giant millipede. I’d show you, if I had a picture!

As long as your imagination is cranking away, here’s a visual aid.

I think his cousin is living in my bathroom shower right now.

Tell me about it

Old news.

Nothing gets between a fiercely protective mother spider and her children. Dripping tree resin trapped adult female spiders and baby spiderlings about 99 million years ago, forever showcasing the maternal care exhibited by these arthropods, according to new research.

One of the awkward things about raising spiders is that they don’t just have a few babies, and they don’t just dribble them out a few at a time over a long period…no, when spiders have babies they have a whole lot of them all at once. Yesterday, on top of all the teaching I do on Tuesdays and Thursdays, I had to feed all the spiderlings I’ve sorted out into individual vials, and then I noticed another egg sac had hatched out into a vast cloud of hungry, tiny arthropods, demanding a meal too. I’m nearly out of flies! I’m going to have to double the quantity of flies I grow just to keep up with the ravenous horde!

No one ever talks about how it was a tender parent and affectionate partner

No. It’s always “underwater killing machine” this and “largest creature of its age” that. Consider the accomplishment of growing to become one of the largest animals on the planet during the Ordovician, instead.

Look at you! Scarcely out of the Cambrian, and already 2.5m long, with a sophisticated sensory system, clever system for maintaining equilibrium in the ocean, and beautifully adept tentacles. Be proud, great brave mollusc! You were more than just a murder monster.