The Amazing Four-Sided Herringboned Ice Cream Cone (with creamy polyp center?)

The farther back you go, the less familiar the lifeforms. Obvious, no? And yet the pattern is not a simple one to one relationship. For example, the Cambrian was a relatively brief time in which the invertebrates collectively decided that "anything goes" and did their darnedest to fulfill that maxim. Many groups didn't hack it and disappeared before the Ordovician. From the Ordovician to the Permian, the shallow seas were filled with bryozoans, brachiopods, and crinoids, with growing numbers of rugose and tabulate corals, mollusks, and fish. The dominant groups of the Paleozoic were greatly reduced or wiped out altogether at the end of the Permian. Almost all of the enigmatic or otherwise difficult-to-classify groups kicked the bucket by the Permian–Triassic extinction, with a few exceptions such as the bellerophont snails (or monoplacophorans), the conodonts, and today's entry, which all persisted into the Triassic for reasons known only to them. The post-Cambrian bryo-brach-crinoid seafloor communities were replaced by Mesozoic communities dominated by mollusks, stony corals, echinoids (sea urchins), and cartilaginous and bony fish. With the end-Cretaceous subtraction of the ammonites, belemnites, certain groups of bivalves, and marine reptiles, and the addition of marine mammals, this becomes the typical modern marine assemblage. Today, many of the extinct Paleozoic groups appear strange, which is a bit unfair because they were just being the best filter feeders/detritivores/algal symbionts they could, and because there are plenty of unusual things alive in the ocean this very instant. Some of them, however, seemingly went out of their way to stand out. One example follows below the fold.

Corals of the Twin Cities

The Ordovician seas of the Twin Cities would have been unfamiliar in a lot of ways. There were no sharks, no bony fish, no marine mammals, no seabirds. No driftwood bobbed in the water. There were no octopuses or true squids, no lobsters or crabs scuttling about. The kings of the echinoderms were not sea stars, brittle stars, and sea urchins, but crinoids. A diver would see a Lilliputian sea-scape featuring cm-scale brachiopods, profusions of bryozoans, and "forests" of sea lilies, traversed by trilobites. Snails, of course, would provide a common point of reference. "Are there no corals?" you ask, thumbing through your waterproof guidebook as you try to figure out if you have just stepped on an inarticulate brachiopod, a bivalve, or a monoplacophoran. Well, yes, there are corals; it's just they are all representatives of groups that have been extinct since the end of the Permian (that pesky Permian–Triassic extinction).

Chuanqilong and Tambatitanis

So I finish the Generic History of Dinosaur Paleontology series on July 20th, and four new genera come along. Of course, it's not quantity but quality, and a year with Anzu and Kulindadromeus will be remembered fondly. Every dinosaur should have its day, though, even if they aren't enormous crested caenagnathids or feathered ornithischians. Two of the most recent genera are in freely accessible publications and represent significantly different but still generally overlooked branches of the dinosaurian tree. They are the titanosauriform sauropod Tambatitanis and the ankylosaur Chuanqilong.

Sponge detective: when faunal lists go bad

I set out to do something simple, really I did. All I wanted to write was an introduction to sponges and a quick description of the forms known from the Twin Cities region. I already had a list of appropriate species, and I knew that most of the original forms weren't actually sponges, which I thought would make things easier. "There's only a couple left, that's not too bad." Then I made the mistake of checking into those leftovers. It turns out that you can never assume a classification for early Paleozoic sponge-like things. There's always room for an argument. In paleontology, the answer to any question always includes "start digging," whether it be rocks or research, and, frankly, isn't some mystery more interesting than a list?

Where to see metro geology, part 6: odds and ends

And now, to complete, more or less, my other series:

I've already hit most of the best places to see Twin Cities bedrock geology up close, and there isn't really much need to flog this further. So, to wrap up things, I'm collecting a few stray thoughts on other areas. There is one other location that is supremely worthy of its own post, and if you are tuned in to the local fossil-hound scene you can guess exactly what it is, and also why there's not much of a point in discussing it now. Thus, the Brickyard of Lilydale will wait.

Previous entries:
Lock and Dam 1/Ford Bridge area
Minnehaha Regional Park
Coldwater Spring
Fort Snelling State Park
Shadow Falls Park

Where to see metro geology, part 5: Shadow Falls Park

Having worked the dinosaurs out of my system for a couple of weeks at least, it is time to return to the Twin Cities. Today's location is one of my favorite places. I first visited it when I was an undergrad at the University of St. Thomas around the turn of the century. This may surprise some of you (well, if this is the first post you've read), but the non-scholastic aspects of college life were utterly lost on me. I did some writing and reading, learned how to kind of flail at a guitar in a rhythmic fashion and sing at the same time, and started the world's drabbest-looking website on dinosaurs. It's amazing how these things will occupy you. In my hectic schedule I also found time to spend poking around the network of goat trails along the Mississippi gorge, which is where the subject of this post comes in.

The generic history of dinosaur paleontology: 1990 to 2014

We come now to the end of this series (previous installments 1699 to 1869, 1870 to 1899, 1900 to 1929, 1930 to 1969, and 1970 to 1989). 1970 to 1989 was the heart of the Dinosaur Renaissance, with its "dinosaur heresies"; as you might guess, when heresies last long enough, they stop being heretical. Funnily enough, for everyone who became interested in dinosaurs after the mid-1980s, the Dinosaur Heresies are a lot closer to the Dinosaur Orthodoxies. You'd have trouble selling a book with that title, though.