Fossils Found in the Calvert & Choptank formations at the Calvert Cliffs of Maryland

Other Vertebrate Fossils here include:

Skates and Rays, Bony Fish, Reptiles, Marine Mammals, Other Stuff

(The smallest divisions in the ruler are 1/8")

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Myliobatiformes order (Rays) Rays are related to Sharks and Skates, as they are all in the Chondrichthyes Class. Fish in this class have a skeleton made of cartilage instead of true bone. What this means for the fossil collector is bones from these animals seldom fossilize. Occasionally a vertebra may be found, however mostly the hard shark teeth and ray crushing plates are found.

Myliobatidae family (Eagle Rays) Today, the bay is home to the Cownose Ray (Rhinoptera bonasus), an Eagle Ray which can get as large as 3 feet in length. If you are boating, or snorkeling, you can sometimes catch them basking in the sun near the surface of the water. Here, we were visited by a large one while snorkeling In the Calvert & Choptank Sea, there was a wide array of genus of Eagle Ray in the bay, that included many tropical forms not found here today. As a result, identifying crushing plate fragments commonly found on the beaches are very difficult. Some of the common genus include Aetobatis (Bonnet Rays), Aetomylaeus (Smooth-tail Eagle Rays), Myliobatis (Eagle Rays), and Rhinoptera (cownose rays) which inhabit the bay today.

Ray crushing plates Rays have modified teeth that form flat crushing plates. These crushing plates are adapted for eating mollusks and crustaceans on the sea floor. They suck their prey up like a vacuum and simply crush them between their upper and lower crushing plates. Most Ray fossils found are tiny fragments of these crushing plates. These fragments can sometimes be difficult to identify to a genus level.

Aetomylaeus sp. (Smooth-tail Eagle Ray partial crushing plate)

This plate came from a large species of Aetomylaeus, which was probably around 6 - 7 feet in width. Partial crushing plates, like this one, are very difficult to find due to their fragile nature. Amy found this one still in a big clay pebble, probably from Zone 9. A piece of the pebble was missing. This missing part contained the rest of the plate! We figure another collector saw the plate piece in the pebble fragment, and took it without noticing the rest of the plate in the rest of the pebble. Here are some pics of it when it was found in the pebble. The left view is the side that did the crushing, the right is the back side of the plate Formation: Calvert, Plum Point member, Zone 9 Age: Early - Middle Miocene ~ 18-15 m.y. Location: South of Brownies Beach, Calvert Co., MD Size: ~ 3.5 x 2" (88 x 50mm) Date: Summer 2002

Aetobatis sp. (Bonnet Ray partial crushing plates) Another Ray in the Myliobatidae family commonly found at the cliffs is the Bonnet Rays.

Imaged here are upper Bonnet Ray plate fragments. They are easy to identify as the plate elements are "V" shaped. Lower plate fragments are more difficult to identify as the fragments look closely like Myliobatis sp. Formation: Calvert, Plum Point member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD

Myliobatis sp. (Eagle Ray Dental Plate fragments)

These are probably fragments of Eagle Ray dental plates. Formation: Calvert, Plum Point member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD Size: ~ 1" (25mm)

? sp. (Ray dermal scute) Rays have body armor (scutes) under their skin on certain places of their bodies. The tops of them have what looks like an enamel scale sticking out, while the undersides look like rock fragments. Since the undersides look just like rock fragments, they can be difficult to spot.

This is the top view of a small one. Notice the scale like structure of the scute. Formation: Calvert, Plum Point member Age: Early - Middle Miocene ~ 18-15 m.y Location: Randle Cliffs, Calvert Co., MD Size: 3/4" (19mm)

? sp. (Ray tail spine)

These are fragments of ray tail spines. Formation: Calvert, Plum Point member Age: Early - Middle Miocene ~ 18-15 m.y Location: Randle Cliffs, Calvert Co., MD Size: usually < 1" (25mm)

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Bony Fish

?Acipenser sp. Sturgeon Sturgeon dermal plate fragment Identification based on Purdy et al (2001, p.161).

I believe this is a tiny fragment of a Sturgeon scute. For an image of a better scute fragment, look at the scute on the Lee Creek collection page. Formation: Calvert, Plum Point member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD Size: ~ 1/2" (13mm)

Reptiles

Crocodilia order (Crocodiles)

Thecachampsa antiqua (Leidy, 1852) Crocodile tooth Identification based on Myrick (2001, p.222) According to Myrick (2001, p.222), since there is a large variation in tooth shape in Thecachampsa dentitions, and there are no important morphological differences between the skulls of crocodiles found in the Chesapeake Group and other tertiary deposits, all the crocodiles should be assigned to T. antiqua.

This is one of the best croc tooth I've ever seen. Even though it has no root, It's beautiful. Looks like it came out of the mouth yesterday. Click on the pic to see the trip it was found on. Formation: Calvert Age: Middle Miocene ~ 15-12 m.y. Location: Chesapeake Bay Area Size: 2 1/2" slant height (54mm) Date: April, 2007 TRIP

This is the most worn Croc tooth I have ever seen, however, it is a very nice reddish brown color. Formation: Choptank Age: Middle Miocene ~ 15-12 m.y. Location: Matoaka cottages, Calvert Co., MD Size: ~ 7/8" (23mm)

Testudine order (Turtles)

Turtle Vertebra

After being misidentified for over a year, I finally realized this is most of a turtle vertebrae. The first pic is the side that connects to the neural scute, and the last is a side view, where the rib would attach. I think determining its Genus would be nearly impossible due to the poor condition of the vert. Formation: Calvert, Plum Point member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD Size: ~1 1/4" by 6/8" (31mm by 18mm)

Cheloniidae family (Hard-shelled Seaturtles)

Syllomus aegyptiacus Carapace of a Hard-shelled Sea Turtle

Click on the pic for more info/ better pics!

I found most of a turtle carapace (top of a turtle shell). It is in kinda bad shape, due to the waves beating it up.. It was found in a chunk of cliffies along the water. Click on the image for up to date pics, and more information. Formation: Choptank (zone will be determined shortly) Age: Middle Miocene ~ 15-12 m.y. Location: Near Kenwood Beach, Calvert Co., MD

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Marine Mammals

Pinnipedia order (Seals, Walrus, etc..)

Phocidae sp. Seal Cervical Vertebra (C-3 to C-7?) Identification based on Timmerman (1997, p.18).

This looks almost identical to a seals' 3 through 7th cervical (neck) vertebrae. It was found near the base of a cliff partially in clay, with the spinous process shattered, lying around it. We did our best to piece it together. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y Location: Randle Cliffs, Calvert Co., MD Size: ~3 7/8" by 2" wide (98 by 51 mm)

Cetacea order (Whales)

Odontocete sub-order Toothed Whales (Including Dolphins and Porpoises)

Squalodon sp. tooth A Squalodon, or"Shark-toothed whale" was a type of primitive toothed whale belonging to the extinct Squalodonotidea family There are 2 species present at the cliffs, S. calvertensis, and S. tiedemani. I don't know which species this is. For more information about squalodons, please take a look at the squalodon article, and additional information in the articles section of this web page.

This is probably a worn pre-molar (tip of tooth, and bottom of root are missing). Squalodon teeth are very hard to find, and much rarer than shark teeth, as whales do not constantly loose their teeth like sharks do. Also, these are less common than the more modern looking Mysteceti, or baleen whales, found here. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y Location: Plum Point, Calvert Co., MD Size: ~ 2 1/4" (57mm)

Kentriodontidae and Eurhinodelphidae family (extinct Porpoises, Dolphins, etc..) There were perhaps a dozen or so genus of porpoise in this area in the Miocene. Some of the common genus includes the extinct Kentriodon and Eurhinodelphis genus. For more information about the Eurhinodelphis genus, look at the additional Eurhinodelphis information in the article section, and the article about an excavated Eurhinodelphis.

Dolphin-Porpoise Teeth Porpoise teeth are much rarer than shark teeth, as porpoises do not continuously loose their teeth. Also, it is more difficult to spot porpoise teeth, as they tend to roll around in the waves. They are usually found by sifting in the pebble areas.

This is a larger than normal porpoise tooth. Click on the pic to see the trip it was found on Formation: Calvert Age: Early - Middle Miocene ~ 18-15 m.y Location: Chesapeake Bay Area Size: ~ 1 1/2" (38mm)

These are some kind of primitive porpoise teeth. There were numerous species, but I have no clue how to further identify them. With that said, the teeth are most likely from the Kentriodon and/or the Eurhinodelphis genus. Both genus have small teeth such as these. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y Location: Randle Cliffs, Calvert Co., MD Size: ~ 5/8" (16mm)

Porpoise Periotic ear bone Ear bones are difficult to spot, as they look like pebbles. It takes a trained eye to spot these.

These are porpoise inner ear bones. They are often mistaken for rocks, especially if they are worn such as the ones in the image. The inner ear bones (the tympanic bulla and periotic) are made from very dense bone, and therefore, often fossilize. A porpoise bulla can be seen on the Lee Creek collection page. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Willows, Calvert Co., MD Size: ~ 1/2 to 1" (51mm)

Porpoise Cervical Vertebra Identification based on Timmerman (1997, p.18).

This is a porpoise cervical vertebra. They are easily identifiable due to the placement of the processes (mostly missing here), and their thinness compared to other vertebrae. If you notice, this particular vertebrae has the ephesis fused, which means it is from an adult. Since it is from an adult, and is relatively small, it probably came from a smaller porpoise genus such as the Kentriodon genus. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Willows, Calvert Co., MD Size: ~ 2" (51mm)

These are two additional porpoise cervical vertebrae. I'm not sure what genus these verts are from. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Plum Pt., Calvert Co., MD Size: ~ larger one is 3.5" (87mm) including the remaining processes Date: Summer, 2002

Complete Porpoise Upper Thoracic Vertebra Identification based on Timmerman (1997).

This is by far the best thoracic vertebra I have ever come across. It was found in a chunk of clay in the water. It took a while to prep. I also left this fragile vert in matrix to help preserve it and to display it. Click on the pic for images of finding it, and preparation. Formation: Calvert, Plum Point Member, Zone 10 Age: Middle Miocene ~ 16-15 m.y. Location: Randle Cliffs, Calvert Co., MD Date: May 2003

Porpoise Thoracic Vertebra Kentriodon sp. vertebra

This appears to be a thoracic vertebra of a small species of Kentriodon porpoise. The processes are obviously missing. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y Location: Willows, Calvert Co., MD Size: ~1 1/8" (28.5mm)

Porpoise Misc. Vertebra Identification based on Timmerman (1997).

These three vertebrae are most likely from Porpoises The middle one is the typical condition they are in when found on the beaches. The far right one is a caudal (tail) vertebra. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: middle one is from Randle Cliffs, the others are from Plum Pt., Calvert Co., MD

Epiphyses from a Porpoise Vertebra "Cookies" Identification based on Timmerman (1997, p.4).

Epiphysis is a part of a bone (usually the end) that ossifies separately from the bone. The epiphyses also attache to the bone at a later date. So, in a juvenile, the epiphyses are usually not yet attached. When a juvenile porpoise or whale dies, the epiphyses often separate from the bone before fossilization. The detached epiphyses from the vertebrae of juveniles resemble cookies. The far right vertebra in the "misc vertebra" picture has its epiphysis missing. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD Size: ~1 3/8" (34mm) diameter, 1/2" (13mm) thick

Porpoise Rib... most of one Identification based on Timmerman (1997).

This is most of a porpoise rib. It appears to be a rib from the rear of rib cage, or a floating rib. It was dug out of a chunk of freshly fallen zone 10, however, before I found it, I smashed the hammer through the center of the rib, thus loosing about 1/2" of the middle of the rib. It is also curved more than this flat image shows. Notice the small bite marks all over the rib, they are hard to see in this image. Formation: Calvert, Plum Point Member, Zone 10 Age: Middle Miocene ~ 16-15 m.y. Location: Randle Cliffs, Calvert Co., MD

Mysteceti sub-order (Baleen Whales)

Cetotherium Fragment of a squamosal cranial element from a Cetotherium? (ENGLISH TRANSLATION: Back piece of the skull from an early baleen whale?)

Click on the pic for more info!

According to some very qualified people at an MGS meeting, this is probably a fragment of the squamosal (rear piece of the skull) from possibly a baleen whale (Mysticeti). It was found while snorkeling for fossils. Click on the image for more pictures. Formation: Choptank Age: Middle Miocene ~ 15-12 m.y. Location: Matoaka Cottages, Calvert Co., MD Size: ~ 7" x 7" x 4.5"

Misc Bone Fragments

Small bone fragments, such as rib pieces, and chunks of cartilage are abundant at the cliffs. These are most likely fragments from dolphins, whales, and seals Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD

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Other Stuff

Predation evidence

The white line on the side view is a small gash, probably a scrape mark by a small shark tooth. Also, the puncture marks in the top view may also be from small shark teeth, as there are smaller punctures on the other side, which may be from the opposite row of teeth. Also, look at the porpoise rib in the marine mammals section, it has small bite marks all over it. Formation: Calvert, Plum Point Member Age: Early - Middle Miocene ~ 18-15 m.y. Location: Randle Cliffs, Calvert Co., MD Size: ~1.5" (31mm)

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