Various Internet rumours have suggested that the Archbishop is a super-giant sauropod one third larger than the mounted Giraffatitan specimen MB.R.2181 (formerly HMN SII). This is incorrect.

Figure E. Skeletal inventory of NHMUK PV R5937, “The Archbishop”, showing which bones were excavated by Migeod’ expedition. Based on a skeletal reconstruction of Giraffatitan brancai kindly provided by Scott Hartman: note that this image does not illustrate the shapes or proportions of the Archbishop material. Bones prepared and available for study are shown in white; those still in jackets awaiting preparation in light grey; those excavated by Migeod but apparently lost or destroyed in dark grey.

Migeod’s assessment of the size of the animal was based on the vertebrae: “The [neck] vertebrae found give a 20-foot [6.10 m] length […] The length of the back including the sacral region was about 15 feet [4.57 m]. The eight or nine caudal vertebrae cover about 6 feet [1.83 m]” (Migeod 1931a:90). This gives the total preserved length of the skeleton as 41 feet (12.50 m). By comparison, Janensch (1950b:102) gives lengths of portions of the mounted skeleton of MB.R.2181 as 8.78m (neck), 3.92m (torso) and 1.07m (sacrum) for a torso-plus-sacrum length of 4.99m. On this basis, the preserved neck of NHMUK PV R5937 is only 69% as long as that of MB.R.2181, but since the first four vertebrae were missing and omitted from Migeod’s measurement, this factor cannot be taken at face value. More informative is the torso-plus-sacrum length, which in NHMUK PV R5937 is 92% the length of MB.R.2181.

This is consonant with measurements of individual elements, which compare as follows:

Table 4. Comparative measurements of Archbishop and Giraffatitan elements

ElementMeasurement (cm)ArchbishopGiraffatitanRatio
Torso plus sacrumtotal length4574990.916
C10 (mC4)centrum length991000.990
C11 (mC3)centrum length104100[1]1.040
D4 (mD3)centrum length27360.750
Longest riblength over curve2352630.894
Left scapulocoracoidlength over curve221238[2]0.929
Right humeruslength1462130.685
Right humeruswidth51590.864
Right iliumlength98123[3]0.797
Right iliumheight7996[4]0.823
Femurlength122196[5]0.622
Average0.846

Archbishop measurements taken from Migeod (1931a) and converted from imperial; Giraffatitan measurements are for MB.R.2181 except where noted, and are taken from Janensch (1950a:44) and Janensch (1961).
Notes.
[1] Janensch (1950a) did not report a total centrum length for C11, as its condyle had not been removed from the cotyle of C10; but since the length of its centrum omitting the condyle was, at 87 cm, identical to that of C10, it is reasonable to estimate its total length as also equal to that of C10.
[2] Janensch (1961:181) did not include measurements for the right scapula of MB.R.2181, which is incorporated into the mounted skeleton, but does give the proximodistal length of its right coracoid as 45 cm. Using the 193 cm length given for the similarly sized scapula Sa 9, we can deduce a reasonable total estimate of 238 cm for the scapulocoracoid.
[3] Estimated by Janensch (1950b:99) based on cross-scaling from the fibula and ilium of Find J from the Upper Saurian Marl.
[4] This is the measurement provided by Janensch (1961:199) for the ilium Ma 2, which is incorporated into the mounted skeleton, and which Janensch (1950b:99) considered to match MB.R.2181 very precisely.
[5] Based on a restoration of the midshaft which Janench (1950b:99) calcuated based on other finds.

Individual lines of this table should each be treated with caution: Migeod’s measurements may have been unreliable, and in any case are underspecified: for example, we do not know whether, when he gave a vertebra’s length, he included overhanging prezygapophyses or the condyle. Similarly, we know that Migeod (1931:96) wrote that a rib “was as much as 92.5 inches long”, but we do not know for certain that, like Janensch, he measured the length over the curve rather than the straight-line distance between the ends. And when Migeod says that the ilium “measured 38.5 by 31 inches” we do not know that the height was measured “at the public process”, as Janensch (1961:199) specified.

With those caveats in place, nevertheless, a picture emerges of a sauropod somewhat smaller than MB.R.2181, though by no means negligible. On average, the measurements come out about 15% smaller than those of Giraffatitan.

But this average conceals a great deal of variation. The cervical vertebrae are comparable in length to those of MB.R.2181 (The total of 203 cm for C10 and C11 in the Archbishop, only 1.5% longer than 200 cm for MB.R.2181, is a difference well within the margin of measurement error). The Archbishop’s scapulocoracoid may have been 93% as long as in MB.R.2181. But the limb bones are signficantly shorter (87% for the humerus and a scarcely credible 62% for the femur), and the humeri at least bseem to be have been proportionally more robust in the Archbishop: only 2.86 times as long as wide, whereas the ratio is 3.61 in MB.R.2181. If Migeod’s measurements can be trusted, we have here an animal whose neck is as long as that of Giraffatitan, but whose limbs are noticably shorter. These proportions corroborate the hypothesis that the Archbishop is not a specimen of Giraffatitan.

I know, I know — you never believed this day would come. And who could blame you? Nearly thirteen years after my 2005 SVPCA talkSweet Seventy-Five and Never Been Kissed, I am finally kicking the Archbishop descriptive work into gear. And I’m doing it in the open!

In the past, I’ve written my academic works in LibreOffice, submitted them for peer-review, and only allowed the world to see them after they’ve been revised, accepted and published. More recently, I’ve been using preprints to make my submitted drafts public before peer review. But there’s no compelling reason not to go more open than that, so I’ll be writing this paper out in the open, in a public GitHub repository than anyone can access. That also means anyone can file issues if they thing there’s something wrong or missing, and anyone can submit pull-requests if they have a correction to contribute.

I’ll be writing this paper in GitHub Flavoured Markdown so that it displays correctly right in the browser, and so that patches can be supported. That will make tables a bit more cumbersome, but it should be manageable.

Anyway, feel free to follow progress at https://github.com/MikeTaylor/palaeo-archbishop

The very very skeletal manuscript is at https://github.com/MikeTaylor/palaeo-archbishop/blob/master/archbishop-manuscript.md

Here I am at SVPCA in 2015. I am haunted by the fact that ten years ago at SVPCA 2005, I gave a talk about the NHM’s Tendaguru brachiosaurid, NHMUK R5937. And the description is still not done and submitted a full decade later. Even though it’s objectively one of the most beautiful specimens in the world:

dorsals-ab-composite

So here is my pledge to the world:

By this time next year (i.e. the start of SVPCA 2016 in Liverpool), I will have written and submitted this description. If I fail, I give you all permission — no, I beg you — to mock me mercilessly. Leave mocking comments on this blog, yes; but more than that, those of you at SVPCA are invited to spend the week pointing contemptuously at me and saying “Ha!”

Let’s hope it doesn’t come to that.

Update (6 September): see also.

A few months ago, prosauropod supremo Adam Yates blogged about the Aardonyx cake that the BPI honours class baked in his honour.  In the comments, I mentioned that my wife Fiona once made me a BMNH R5937:D9 cake (i.e. a cake in the form of the more posterior of the pair of nicely preserved dorsal vertebrae of The Archbishop, in right lateral view). At the time, I couldn’t find the photo that I knew had been taken, and Adam asked me to post it when it turned up.

Voila!

And here, once more, is the real thing for comparison:

(Note that the topology of the lateral lamination is spot on, with a single infradiapophyseal lamina which forks into anterior and posterior branches only some way ventral to the diapophysis.  That’s what you look for in a cake.)

Update (21 April)

Silly me, of course what I should have shown is the cake and the vertebra side by side.  Here they are — together at last!

This post is nearly three weeks late — it’s based on a piece of artwork that appeared on 25 September, and which I wanted to write about immediately.  But it got washed away in the flood of camel necks (which by the way is not over yet), and then in the festival of articular cartilage, then by the whole “Amphicoelias brontodiplodocus” thing and the subsequent discussion of amateurs in palaeo, and then by what was already an overdue announcement of my sauropod history paper and the attendant copyright nonsense.  So it’s been a stupidly busy time here at SV-POW! Towers, but now the air has cleared a little, and it’s time to look at this beauty:

 

Life restoration of NHM R5937 "The Archbishop" (Brachiosauridae incertae sedis), by Nima.

 

This would be a beautiful piece of art by any standards — the world can always use brachiosaur art! — but what makes this extra special for me is that it is the first ever life restoration of my very own brachiosaur, BHM R5937, the Tendaguru specimen known as The Archbishop.  It’s by SV-POW! regular Nima, and I am absolutely delighted to see it.  It’s very Greg Paul-like, and I mean that in the most positive sense.  (I may not be a fan of Greg’s taxonomic vicissitudes, but his art is just beautiful.)

Over on his blog, Nima has described in detail how he created this piece, and shows four progressively refined versions (of which the one above is the last) — I urge you to check it out if you’re interested in art, brachiosaurs or both.

Nima’s blog-post also includes a brief history of the Archbishop, mostly taken from my 2005 SVPCA talk.  It’s a good summary, but I do have a few comments to make.  (I typed a lot of this in as a comment to the original post, but Blogger ate my comments as usual.)

  • The specimen is not known as M23, and has never been — that is in fact the designation of the Tendaguru quarry from which is was excavated.  Paul (1988) mistakenly conflated the quarry name with a specimen number, and referred to this specimen as BMNH M23, and Glut’s (1977) encyclopaedia perpetuated the error, but it’s always been R5937.
  • “The giant Brachiosaurus finds of the Germans” are now, of course, Giraffatitan.
  • “Controversy lingered” — well, no, not really.  The problem was worse than that: no-one paid a blind bit of notice to the specimen before 2004.
  • “It turns out the double spine claim was totally bogus and unscientific” — well, we don’t really know that yet.  It’s certainly true that none of the prepared vertebrae (five cervicals, two complete dorsals and an additional dorsal spine) have bifid spines; but Migeod reported these from the anterior dorsals, and it’s not clear that we have those.  A fair bit of material remains in jackets, and more has probably been lost or destroyed.  So it is possible, if unlikely, that one day we’ll open one of those jackets and find good evidence for bifid spines.
  • “Close-up of the Archbishop vertebrae (doesn’t look much like the mitre of an archbishop to me, but who knows” — well, the name The Archbishop is not based on any resemblance of the bones to a mitre.  (Nor is it based on anything else.  It’s completely arbitrary.)

Last 0f all, what about the actual picture?  Well, the long, thin, snakelike neck is beautiful art, but I don’t think it’s great science.  The height of the cervicals that we have for this animal show that the neck would have had to be quite a bit dorsoventrally taller than shown here.  And because there were only 13 cervical vertebrae — 12 if you omit the atlas, which is really a whole nother kettle of badgers, a neck bent into a strongly sigmoid pose like this would exhibit noticable kinks at some of the intervertebral joints — as you can see in giraffes when they twist their necks.

That aside, though, this is great.  Again, I am really delighted that it’s out there.  Congratulations to Nima!

CT-Scanning the Archbishop

November 18, 2009

Last week, for the first time ever, I spent the entire working week on palaeo.  I took a week away from my job, and spent it staying in London, working on the Archbishop at the Natural History Museum.  (For those of you who have not been paying attention, the Archbishop is the informal name of the specimen NHM R5937, a brachiosaurid sauropod from the same Tendaguru area that produced Giraffatitan brancai, and which has been generally assumed to represent that species.)

DSCN7528

Brachiosauridae incertae sedis NHM R5937, "The Archbishop", Cervical U in right lateral view. Photo copyright the NHM since it's their specimen.

My main goal was to take final publication-quality photographs that I can use in the description (which I have committed to try really, really hard to get submitted by the end of 2009).  There’s quite a bit of material (more than for Xenoposeidon, anyway!) — six cervicals in various states of preservation/preparation, cervical ribs, two complete dorsals, two more dorsal centra and a dorsal spine, some scap scraps, a partial ?pubis, a long-bone fragment and “Lump Z“, whatever that is.  What you see above is my best lateral-view photograph of what I’ve designated “Cervical U”.  One of these days, I’m going to do a post on how to photograph large fossils — something it’s taken me five years to get the hang of — but for today, I want to tell you about an exciting adventure with Cervical U.  [Update: I wrote the How To post a few months later.]

Because my other big goal on this trip was to get it CT-scanned.  Thanks to the generosity of John Hutchinson of the Royal Veterinary College, and to the help of the NHM people in arranging a loan, everything was set up for my host Vince Bickers and me to ferry the specimen up to the RVC, scan it and return it.

But first it had to be packed:

The Archbishop, Cervical U, packed and ready for transportation. Behind, Lorna Steel and Sandra Chapman of the NHM, who did the work.

Lorna and Sandra spent a long time looking for a crate big enough to pack the bone in, but came up empty — there was one that was long enough but not wide enough, one that was tall enough but not long enough, and so on.  In the end we sat the bone, on its very solid plaster base, on a plastic pallet, and wrapped it in pillows, bubble-wrap and that blue stuff whose name I don’t know.

As it happened, the scan had to be delayed for a day due to lack of personnel at RVC, but Vince and I took the vertebra up on the Thursday anyway; he had to return to work on the Friday, but I took public transport to RVC for the big day.  Before we went into the scanning room, John showed me his freezer room:

Just a couple of the freezers at RVC

I found it amusing that they have enough Segments Of Awesome that they have to label the various elephant-part freezers differently.  And further down the aisle:

John Hutchinson proudly shows off his dead baby rhino.

Then it was off to the scanning facility, where we found that we had to unpack the vertebra: it was small enough to go through the machine, but there was no way the pallet was going through.  Once we’d unpacked it and removed it, it fit pretty nicely:

The Archbishop's Cervical U all lined up and ready to go through the scanner, courtesy of John and radiographer Victoria Watts.

Because the scanner spits out X-rays in all directions, it’s controlled from a separate room, behind lead-impregnated glass:

Inside the control room

We ran three scans before we got the settings right — we needed more voltage to get through the bone and matrix than we’d first realised, and a filter was causing unhelpful moire patterns.  The third scan was definitely the best, and the one I expect to be working with.

[Boring technical side-note: I plan to use 3D Slicer for visualisation thanks to Andy Farke’s series of tutorials. But, frustratingly, I wasn’t able to load the DICOM files from the scan into that program: it crashes when trying to load them (segmentation fault) even though it works fine on the ankylosaur skull that Andy walked us through in the tutorials.  I fixed this by gluing the 300-odd files together into a single stack file that 3D Slicer was able to read.  For the benefit of anyone else who needs to do this, the command (on a Ubuntu Linux box) was: medcon  -f  *.dcm  -c  dicom  -stack3d  -n  -qc]

Here is an example slice, showing part of the condyle in posterior view:

CT slice through the condyle of The Archbishop's Cervical U, in posterior view. Dorsal is to the left.

The grey blobs at the bottom of the image are the plaster jacket that supports the vertebra; the white is bone, and the light grey inside it is matrix that fills the pneumatic spaces.  I’m showing the condyle here because its cavities are clearly visible: further back in the vertebra, they are harder to pick out, perhaps in part because of the iron bars scattering the X-rays.  It’s notable that this vertebra is less pneumatic than would be expected for a brachiosaurid — by eye, it looks like like the condyle is only 20-30% air, and this slice is not unrepresentative.  Most neosauropods would be at least twice this pneumatic, so we may have an Archbishop autapomorphy here.

I’ve not yet persuaded 3D Slicer to build a 3D model for me, but I’m pleased to say that before I left RVC, John mocked up a quick-and-dirty render of the bone using only density threshholding, and I can at least show you that.

The Archbishop, Cervical U, CT scan 3d model in left ventrolateral view

Here we see the bone from the left side, previously obscured by solid plaster.  From a single static image, it’s not easy to make out details, but we can at least see that there is a solid ventral floor to the centrum … and that those two crossed iron bars obscure much that we would like to see.  You will get more of an idea from the rotating video that this is screencapped from.

Looking at this and comparing it with the right-lateral photo at the top of the post, it’s apparent that the density threshhold was set too high when making this model: all the bone along the lower right margin of the middle part of the centrum is good, but it’s been omitted from the model.  In other words, the vertebra is more complete than this proof-of-concept model suggests.  Hopefully I will shortly be able to show you a better model.

If you’ve been following SV-POW! closely – perhaps a little too closely – you will know of BMNH R5937, a Tendaguru sauropod collected in 1930 on one of the British Museum (Natural History) expeditions, and reported in 1931 by Frederick Migeod (pronounced ‘mee-zhou’). Discovered in the ‘M23’ quarry at Tendaguru, the specimen was assumed by Migeod and all subsequent authors to be another specimen of Brachiosaurus brancai, but what’s notable is that Migeod mentioned several features in the vertebrae of the specimen that really sounded quite un-Brachiosaurus-like. Despite the size and quality of the specimen however, nobody ever got round to studying it properly – until Mike did exactly this. An abstract and talk slides on the specimen can be found here. For whatever reason, the specimen has become known as The Archbishop.

While Migeod wrote about The Archbishop, he never published any illustrations of it (with the exception of a quarry map). I don’t think I’m betraying any secrets by letting on that Mike is working on a full technical desciption of the specimen, wherein it will of course be illustrated properly. Little known however is that The Archbishop has appeared in the literature before, but (unsurprisingly, and in keeping with tradition) has been misidentified as Brachiosaurus. After all, it’s a big sauropod and it comes from Tendaguru, so it must be Brachiosaurus, right? Here’s the proof: it’s p. 94 of David Lambert’s Ultimate Dinosaur Book, published by Dorling Kindersley in 1993. The Archbishop photo is, of course, up there at top right, masquareding as the dorsal vertebrae of Brachiosaurus brancai.

Back in 2017, I showed the world 83.33% of my collection of sauropod-themed mugs. Time passes, and I have lost some of them and gained some more. The tally now stands at eight, and here they are:

My missing Brontomerus mug never did turn up. In the mean time, I have also lost or maybe broken the Sauroposeidon mug, the old black-and-white Archbishop mug, and the single-view Xenoposeidon mug. The dissertation mug still survives, but has faded into total illegibility, so I don’t count it any more.

On the more positive side, the sexual selection mug — second from the right in the old photo, and bottom left in the new one — survives, in fact the only one to have done so. All the others are new acquisitions. Let’s take a look:

Back row, left to right:

  1. The new, improved Archbishop dorsals A and B mug. Unlike the original, this is in glorious colour, and rearranges the elements to show anterior view on the front, and left and right lateral on the sides.
  2. The new, improved Xenoposeidon mug. It’s laid out the same way with the anterior view on the front and left and right lateral views on the sides.
  3. One that Fiona made for my birthday, showing one of the publicity photos from the original Xenoposeidon description: the one of which a newspaper columnist wrote “I wish my husband looked at me the way he looks at this bone”.
  4. A mug made by Mark Witton, which I saw at TetZooCon 2019 and made him an offer for. It shows his own Diplodocus artwork, an update of an earlier piece that he did for Matt, Darren and me to publicise our 2009 paper on sauropod neck posture. (Details here.)

Front row, left to right:

  1. The sole survivor, showing the introductory here’s-what-sauropod-necks-are-like illustration from our 2011 paper on why those necks were not sexually selected.
  2. The sauropod neck gallery used as Figure 3 in my and Matt’s 2013 PeerJ paper “why giraffes have short necks”.
  3. One of the world’s few caudal pneumaticity mugs, using all the illustrations from Matt’s and my 2013 paper, and inspired by the freakily consistent colour palette of those illustrations.
  4. This one needs a bit of explaining. See below.

For reasons that no-one — least of all he — understands, my youngest son bought a pair of Dawn French mugs as a birthday or Christmas present for Fiona. (No-one in our family is particularly a fan, it was one of those random things.) Since then, he has given her five or six more identical mugs.

Because I do not like these, I insist that they hang on one mug tree, and the sauropod mugs on another. It was to break down this mug apartheid that our eldest made for us this final mug, which shows both Dawn French and a reconstruction of the Xenoposeidon vertebra (from my 2018 paper). Where does it live? Usually, it sits on the shelf between the two mug trees.

So this is how things stand. (I drink a lot of tea, so these mugs all see plenty of action.) I really should make myself a new Brontomerus mug, and perhaps a pneumatic variation one.

Accidental anaglyphs

October 16, 2020

Everyone knows that the very first thing you should do to improve your specimen photography is to use a tripod: it eliminates hand-shake and gives you much crisper photos. In most respects, my photographs have got much, much better since I’ve been habitually using a tripod.

But it has meant I’ve not been able to benefit from happy accidents like the one that gave me this 3D anaglyph of the Archbishop‘s Cervical S in dorsal view:

(Do you have red-cyan glasses? Yes? Good! You will be able to appreciate all the delicious morphological information in this photo. No? Go and order some right now — they cost literally a dollar.)

The reason I was able to make this very useful image is because back in the old pre-tripod days I would sometimes accidentally move a little bit between taking two more-or-less identical photographs. Here are the two images that I was able to composite into the anaglyph above:

Each of them is pretty uninformative alone: who can tell one nondescript area of brown bone from another? But when combined, they are extraordinarily more informative. If you don’t have 3D glasses then (A) get some! and (B) you can get some idea of how helpful the 3D information is from the crude wigglegram below, which simply switches back and forth between the two images.

And I can’t overstate how enormously helpful I have found these accidentally sourced anaglyphs as I write the descriptive part of the Archbishop manuscript. Even at this level of crudity, they have shown me several important points of morphology that I would certainly have missed if I’d been working only from my orthogonal-view photos, and saved me from more than one misinterpretation.

The moral is twofold:

  1. When taking specimen photographs, use a tripod — but deliberately get some pairs of shots where the camera is moved to the side by about 7 cm (the distance between the pupils in an average human).
  2. If you don’t have any red-cyan glasses, get some!

Well, one reason is the utterly rancid “block editor” that WordPress has started imposing with increasing insistence on its poor users. If there is one thing that world really doesn’t need, it’s a completely new way of writing text. Seriously, WordPress, that was a solved problem in 1984. As Henry Spencer very nearly said back in the eighties, “thy creativity is better used in solving problems than in creating beautiful new impediments to productivity“.

But enough pointless whining: instead, check out this bad boy:

Taylor (in prep. for 2020: Figure V). NHMUK PV R5937, “The Archbishop”, cervical vertebra V (most anterior preserved cervical vertebra, probably C6), left side still encased in plaster. A. Reconstruction of right lateral view with neural spine, prezygapophysis, diapophysis, condyle, cotyle and cervical rib restored. The prezygapophysis from the succeeding vertebra that has adhered to this element is shown in red. B. Dorsal view with anterior to the right. C. Posterior view. D. Right lateral view. E. Anterior view. F. Ventral view with anterior to the right. Scale bar 20 cm.

Yes, it’s your friend and mine, The Archbishop! It’s a big titanosauriform sauropod excavated by F. W. H. Migeod for the British Museum (Natural History) back in 1930, from the same Tendaguru Formation that yielded the awesome Giraffatitan specimens in the Museum für Naturkunde Berlin.

Yes, I admit I have been working on the Archbishop for more than sixteen years, and that I gave a talk about it at SVPCA 2005, and that I failed utterly to get it done as part of the Paleo Project Challenge 2010, and that as early as 2011 I was in despair about ever finishing it, and that I promised to do it by SVPCA 2016 but didn’t.

But in 2018 I did something significant, which was to actually start writing the paper in public. Now anyone can follow the progress of the project — and it’s progressing. The manuscript currently runs to about fifty printed pages, although that length is inflated by twenty-odd beautiful illustrations — of which the “Cervical V” image above is just one. (Do click through to see it in all its glory.)

So, yeah. That’s the main reason I am not blogging much. Because I am writing the paper. Finally.