Archive for March 13th, 2015

Days Five and Six – Mojave 2015

March 13th, 2015

Day five began at Kelso Dunes - sand, ripples, and Wooster Geologist footprints.

Day five began at Kelso Dunes – sand, ripples, and Wooster Geologist footprints.

Michael for scale.

Michael for scale.

Petroglyphs at Hole in the Wall.

Petroglyphs at Hole in the Wall.

Eric for scale, showing the size of tafoni at Hole in the Wall.

Eric for scale, showing the size of tafoni at Hole in the Wall.

Proof that the Wooster Geologists were at Hole in the Wall.

Proof that the Wooster Geologists were at Hole in the Wall.

And we made a friend at Hole in the Wall.

And we made a friend at Hole in the Wall.

Day five ended with a visit to a lava tube.

Day five ended with a visit to a lava tube.

Day six started with a visit to the Resting Springs Welded Tuff.

Day six started with a visit to the Resting Springs Welded Tuff.

Check out the fault at Resting Springs Pass.

Check out the fault at Resting Springs Pass.

We channeled our inner Dr. Mark Wilson and searched for fossils in the afternoon.

We channeled our inner Dr. Mark Wilson and searched for fossils in the afternoon.

Olivia found this trilobite! Wow!

Olivia found this trilobite! Wow!

We ended the day with date shakes at the China Ranch. Yum!

We ended the day with date shakes at the China Ranch. Yum!

Wooster’s Fossil of the Week: A new crinoid genus from the Silurian of Estonia

March 13th, 2015

Velocrinus CD-interray lateralIt is my pleasure to introduce a new Silurian crinoid genus and species: Velocrinus coniculus Ausich, Wilson & Vinn, 2015. The image above is a CD-interray lateral view of the calyx (or head), with the small anal plate in the middle-top. (This will make more sense below.) The scale bar is 2.0 mm, so this is a small fossil. It was captured by the Crinoid Master himself (my friend and colleague Bill Ausich) from the Middle Äigu Beds of the Kaugatuma Formation (Upper Silurian, Pridoli) at the Kaugatuma Cliffs of Saaremaa Island, Estonia. It is described in the latest issue of the Journal of Paleontology. Here’s a link to the abstract. (This is the first issue produced by Cambridge University Press, so we’re honored to be part of publishing history.)
Velocrinus E-ray lateralHere is another view of the calyx, this time looking laterally at the E-ray.
AusichWilsonVinn_Fig3This figure explains the calyx views we see above. It is a plate diagram of Velocrinus coniculus. Imagine it as what the crinoid would look like if we could separate all its preserved ossicles and lay them out. The radial plates are black; the anal plate is shown stippled and marked with an “X”; the other letters indicate the particular rays. The artwork, and the images above, are from Bill Ausich.

The genus Velocrinus is defined this way in the paper: “Crotalocrinitid with a calyx cone shaped, lacking stereomic overgrowths, comprised of relatively large plates; infrabasals not fused, visible in lateral view; two anal plates; primaxil minute, not visible in lateral view; fixed brachials present; free arms not laterally linked; anus on tegmen; (nature of tegmen plating unknown).” This certainly is opaque to most readers. Trust us — it separates this new genus from all described before. Velocrinus is derived from the Latin term velo, which means to cover or conceal (think “veil”). It refers to the tiny primibrachials, which are not visible in lateral view. The species name coniculus refers to the cone-shaped calyx.
Kaugatuma070511Velocrinus coniculus is known only from the Kaugatuma Cliffs locality on Saaremaa Island. This is one of my favorite outcrops in Estonia. The extensive bedding-plane exposures are rare in the region. They show hundreds of holdfasts (essentially roots) of crinoids, some very large. The deposit was a relatively high-energy carbonate sand shifting through a forest of tall crinoids rooted in the sediment. Palmer Shonk (’10) did an excellent Senior Independent Study with rocks and fossils we collected from this place. The site shown above, by the way, was the location of a Soviet amphibious landing in November 1944.
KaugatumaCrinoidStem070511This is a close look at a bedding plane of Middle Äigu Beds of the Kaugatuma Formation. The crinoid stems are robust and abundant. Oddly enough, we’re still not sure what genus is represented by the large stems and holdfasts. The calyx of Velocrinus coniculus is far too small to have been associated with them. I suppose this means we need another expedition to Estonia!

This is the 1000th post in the Wooster Geologists blog.

References:

Ausich, W.I., Wilson, M.A. and Vinn, O, 2012. Crinoids from the Silurian of western Estonia. Acta Palaeontologica Polonica 57: 613–631.

Ausich, W.I., Wilson, M.A. and Vinn, O, 2015. Wenlock and Pridoli (Silurian) crinoids from Saaremaa, western Estonia (Phylum Echinodermata). Journal of Paleontology 89: 72-81.

For Our Wooster Family

March 13th, 2015

IMG_0021Here’s a photo of a peaceful sunrise at the Desert Studies Center to let our WOODS friends know that our thoughts are with them.