What do Delaware, Hawaii, and Rhode Island have in common?

Answer: They are the only three U.S. states for which I can't find a record of a mastodon or mammoth.

Hawaii is not exactly a surprise. Certainly proboscideans can swim, but if you want a large mammal that can swim halfway across the Pacific Ocean without dying, it's going to look and function suspiciously like a cetacean instead.

Delaware and Rhode Island, on the other hand, doubtless had mammoths and mastodons tromping over them at some point, because they're surrounded by states (and submerged coastal plains) that have their fossils. They're just both small states not blessed with the most helpful geology, and mantled by urbanization. Rhode Island gets an additional strike from being subjected to glaciers. Someday the fossils will turn up, though. Maybe there's already something; maybe somebody has a funny-looking doorstop they found in 1973 and never paid much attention to, or there's a notice in a local paper published in 1989 about a couple of campers who found a tooth and turned it over to a local historical society, or somebody will hop into the comments of this post and say, "Hey, ya numbskull, ya missed this!"

Now, the nitty-gritty: every once in a while I'd wondered how many states have records of mammoths or mastodons, and occasionally puttered in a source or two. This time I decided to be more thorough. I checked the Hay inventories, Neotoma (which has the old FaunMap contents), and the Paleobiology Database for starters. These three together narrowed down the list of absences to Delaware, Hawaii, New Hampshire, and Rhode Island. If you're curious: Hay didn't have mammoths or mastodons in those four plus Maine and basically omitted Alaska, but had all the rest plus the District of Columbia; Neotoma was missing the four plus Alabama, Mississippi, North Dakota, Vermont, and D.C.; and the PBDB was missing the four plus Connecticut, Louisiana, Massachusetts, Maine, New Jersey, North Dakota, Vermont, and D.C. This is why it's important to check multiple sources; no one source has everything.

Putting aside Hawaii, that left Delaware, New Hampshire, and Rhode Island to check out. Now was the time to drill into the resources of various search engines and museum databases/iDigBio. For the record, I leaned on Google Scholar, Google Books, and the news tab of regular Google (not Google News), with various permutations of "mammoth", "mastodon", "Mammuthus", and "Mammut" plus a state, with additional terms as necessary to knock out particularly obnoxious false positives. This eliminated New Hampshire, which now has a record from a find on land after a couple of teeth found nearby offshore. For a short time I'd thought I'd found one for Delaware, thanks to a short piece in the Winter 1994 issue of "First State Geology" (p. 3). The article mentioned that Jeremy Cloutier of Milford had donated a mastodon tooth to the Delaware Geological Survey, but the tooth derived from offshore clam dredging and therefore doesn't count for our purposes. So, for now, we're still at Delaware, Hawaii, and Rhode Island. (Still a few field days 'til Christmas, if you're feeling like pulling off a Christmas miracle!)

"Archie", the world's largest mounted Columbian mammoth skeleton, on display in Elephant Hall, University of Nebraska State Museum.