Pseudofossils

Fall and early winter offer low lake levels and wide beaches. The boats are all put away, so when there is a decent day with calm winds it’s a good time to reconnect to the lake with a beach walk. I live in a land of gravel and cobble beaches and pebble picking is a favorite pastime for us here on the south shore. When walking with other less experienced pebble pickers, I’m often asked about pebbles and cobbles with possible fossils. (My sister calls them ‘Memory Rocks”. We do have several types of fossils but not every pebble with a spot or hole contains a fossil. The real experts call these “Dubiofossils.”

This limestone pebble contains cylindrical segments (viewed on end) from a fossil crinoid ( sea lily). There seem to be two distinct types of center holes. Two different species??? These round discs are very common local fossils.

In 2019 a team of paleontologists announced the discovery of a new crab like creature from the Triassic. However, the discovery soon received a rebuttal. Other specialists noted that what had looked like a separate animal was actually a piece of another fossil creature, being the head of a large fossil insect.

The limestone cobble above contains a cephalopod fossil about four inches long. These relatives of the chambered nautilus are common beach pebble fossils here. This is a side view of the horn shaped shell showing the segments or sections. This distant squid relative lived at the front of its tusk like shell.As the critter grew it added a larger chamber. Orthoceras means ‘straight horn’ and is the name of one common group of these ancient mollusks.

Fossils are very popular with beach combers and with the public in general. So I shouldn’t have been surprised to find when I Googled ‘fake fossils’ that the first results were “buyer beware” warnings of counterfeit fossils. Bright colors and cheap prices are a giveaway according to one reputable seller.

Examples of fakes from the Web.I haven’t seen any on the beach. Yet.

Sometimes fakes are simply carved from or painted on rocks. And sometimes fragments of real fossils can be artfully combined to make an expensive “high quality” specimen. A lot of the fakes originate from China. Some are good enough that they have even ended up in museum collections.

Not every multicolored rock with a hole or a distinctive embedded shape has a fossil in it. In the photo above you see a juvenile alewife on a water rounded dolomite rock probably dislodged from someone’s shoreline rip rap. The patterns in the rock are not fossils. The rip rap stones sometimes do have some cool fossils, but this is not one. Below is a nice cast type fossil in a Fair Haven Beach boulder placed by the swim beach.

The white scratches on this large rock below are not fossils but they are interesting reminders of the hard life of a stone during glaciation.

This stone had recently eroded out of a drumlin bluff that fronts this undeveloped beach, after being embedded in glacial till for thousands of years. The scratches suggest it was probably dragged over other rocks by ice movement on more than one occasion ( since the white marks are not all parallel.)

All of these limestone beach pebbles in the photo below contain a ‘hash’ of fossils. Because the critters were mashed, broken and otherwise deformed during the process of being buried to become stone, they may not be easily identified. Some are in cross section. Others are seriously distorted and jammed together. The second pebble from the right has a white circle- probably a cross section of one of the cephalopods about the size of the profile critter in the first photo above.

The west side village park in Fair Haven located on the barrier bar next to Fair Point Marina is a really good place to look for fossils.

And you don’t need a fossil collecting permit yet…

This is Fairplay Colorado’s famous “beach”, left by after a dredge chewed up the bottom of a tributary of the South Platte in its search for gold. Here’s an old photo of the dredge. The abandonned machine is gone now. You can see the piles of gravel behind it.

Here’s your author in search mode. Yesterday I found a really cool cobble on the beach that had Three ! big cephalopods in it. Happy Hunting!

Shameless self promo here-more fossil info in Natural History of Lake Ontario