Tag: limestone

The Crocodile and the Countertop

Italian paleontologists have been on a roll of late, and they haven’t even had to go out in the field. Late last year came reports of the dinosaur in the duomo. Now, comes the tale of the countertop crocodile. The new story begins in 1955 in Portomaggiore (Ferrara, Italy), when stonecutter Mr. S. Pasini observed what he thought were fossil bones in a block of yellowish-red limestone destined for a countertop. After the cutting the block into four slabs, Pasini saved the stone. A year later paleontologist Piero Leonardi described the fossil as a cross section of a crocodile he called the “Coccodrillo di Portomaggiore.”

Cross sectioned slabs from Gondwana Research (In Press, available online August 7, 2010) Scale bar = 20cm.

Two of the slabs eventually ended up at the Museo Geologico Giovanni Capellini in Bologna, where they they sat undisturbed until 2009 when paleontologists Federico Fanti and Andrea Cau studied them. They concluded that Leonardi’s crocodile was a new species and the oldest member of the Metriorhychidae, a diverse and curious group of marine crocodilians, which existed from about 171 to 136 mya. They were fierce, pelagic, piscivorous predators. Fanti and Cau named the new species Neptunidraco ammoniticus or “Neptune’s dragon from the Rosso Ammonitico Veronese Formation.”

Neptunidracos‘ streamlined body, Illustration by Davide Bonadonna

Neptunidraco is the oldest known member of the Metriorhychidae group and did not look like any modern crocodile. They had streamlined skulls, a vertical tail, and a hydrodynamic body, all features well adapted to a marine lifestyle. Cau describes Neptune’s dragon as “more like a dolphin than a croc.” Based on their anatomy and teeth, they ate small, swift fishes. They may have ventured onto land to lay eggs. Later Metriorhynchids were more robust and could have eaten armored fish and large marine reptiles.

Happy geologists Cau and Fanti (from Cau’s blog)

Rosso Ammonitico, also known as Verona Marble, is a Middle Jurassic age, generally reddish limestone rich in ammonites, hence the name. It formed in deep water as fine grained sediments settled into the Tethys Sea on the margin of Gondwanaland. The specific quarry was near Sant’Ambrogio di Valpolicella, about 10 miles northwest of Verona. (The fossil-rich slabs come from a more yellow part of the quarries, known as “ammonitico giallo.”) Used since Roman times, Rosso Ammonitico can be found at the Arena in Verona, the Battistero in Parma, the Palazzo Ducale in Venice, the Cathedral in Cremona, and the Galleria V. Emanuele in Milan. (On the VertePaleo list serv, the reporting of this story led to some amusing anti-limestone-countertop comments. When I was in Bloomington, Indiana, working on my chapter on the Salem Limestone, I remember seeing builders touting the limestone countertops of a new rental units. To each his/her own.)

Ammonite from Baptistry (Battistero) of Parma (from Wikicommons)

The publication of the story apparently has ruffled a few feathers in Italy. On Andrea Cau’s blog, he notes that one famous Italian geologist offered critical comments on the discovery (saying it wasn’t truly a discovery since the fossil had been known since 1955) and the bigger implication that it provides a new understanding of the evolution of these intriguing marine crocodiles. Cau believes that the conflict results in part from a generational difference and a clash of paradigms, where the young upstarts are willing to reconsider, restudy, and reevaluate past concepts and specimens. He recognizes that their discovery does not change the world but it “is a beautiful piece of a huge mosaic called paleontology.” (Translation from Google Translator.)

Moreover, isn’t what Cau and Fanti did part of what makes science so appealing and such a valuable way to understand the world around us. We should applaud them for looking carefully, for struggling with understanding what they saw, for asking questions, for drawing new conclusions, and for learning from those who came before. And yes, their new discovery is a thing of beauty.

Airport Fossils

Trapped at SeaTac Airport in Seattle with nothing to do?  I am sure the people stranded there would rather be someplace else but the extra time will allow intrepid travelers to explore the many fossils found in the walls of the food court in concourse A.  The fossils make a captivating cast of characters that lived 155 million years ago in what became Germany.  During the Jurassic Period when dinosaurs roamed the land, a shallow sea covered much of Europe.  Many critters from that sea are now preserved in the tan to gray limestone cladding walls at SeaTac. 

155-million-year old ammonite – Good examples are in the pillars just past the security check, particularly the one nearest Ex-Officio.

The stone is known as the Treuchtlingen Marble, although it is not marble but limestone.  It was never metamorphosed.  As the animals died they settled to the bottom of the sea.  The most common fossils are sponges, bottom dwelling, filter feeders that formed small mounds.  They may be round, straight, or irregularly shaped and are darker than the surrounding limestone.  Also common are ammonites, coiled-shell animals that resemble a top down view of a cinnamon roll.  The biggest ones in the German limestone are about five-inches across, whereas the largest ones that ever lived were six feet wide.  Ammonites were prevalent marine predators in the Jurassic but went extinct at the end of the Cretaceous.  Their modern relatives include squids, chambered nautiluses, and octopi.  

You can also find another squid relative, belemnites, which look like a cigar.  They are dark brown and somewhat shiny.  Also seek out brachiopods, clam-shaped animals known as lampshells due to their resemblance to ancient oil lamps.  Unlike clams, brachiopods cannot move and feed by opening their shell and consuming bits that float by.  And finally, the white specks that look like oatmeal are single-celled sea dwellers called foraminifera. I hope this at least helps some people pass the time at SeaTac.