GREEN SCENE

Unearthed tree stumps filled with ancient past mysteries

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Fossils can be found everywhere, and we have our share here in New York.

Many years ago, my husband — who loves to drive — and I (who does not) drove three hours to Gilboa in Schoharie County to visit the Gilboa Museum and Juried History Center. The draw was the remains of the bulbous bases of early trees that sit outdoors surrounding the museum. The bases have a circumference of between 20 and 40 inches, flaring out considerably more at the base bottom.

These fossils are in the form of casts, meaning the remains were formed from sediment deposited inside the plant cavities as the organic matter decayed.

In modern trees, a bulbous base “indicates an unstable or water-logged condition since (the tree) tries to correct instability by adding more tissue to the trunk base and/or adding an elaborate root system,” according to researcher James Boyer.

A pleasant surprise transpired as I was researching this column. I happened upon Boyer’s master’s thesis discussing the fossil materials found at Gilboa. The now-Dr. Boyer teaches paleobotany at the New York Botanical Garden, and I was fortunate to take his class several years ago. I also appreciate and acknowledge his further help in organizing the materials for this column.

The first of these botanical fossils came to light in 1869 when a flood swept through the area unearthing these casts. Over the years, numerous other fossils have been found. Sir John William Dawson, a 19th century Canadian geologist, now considered a father of paleontology, examined many of the Gilboa fossils and described them in his 1888 book, “A Geological History of Plants.” He may, however, be best known for his work on ancient plants from the late Carboniferous Period of 310 million years ago, found in the Joggins Cliffs near the Bay of Fundy in Canada when the area was a rainforest.

The remains found in Gilboa, in the Riverside Quarry at the Schoharie Reservoir, however, are considerably more ancient, being from the Devonian Period from between 419 and 359 million years ago, more specifically from that part of the Middle Devonian now referred to as the Givetian of a little more than 380 million years ago. In the scientific literature, the period had been given other names, including the Erian (hint: This explains something about the eventual naming of the tree).

Museums and reproductions have spoiled us by presenting finished examples of ancient plants and animals as if these were found complete in excavation sites. Unfortunately, that is often not the case. Bits and pieces turn up at different sites, and it is intellectually challenging to determine which remains fit together. 

At Gilboa, the casts of the tree bases were found standing upright, but were otherwise incomplete. Scientists had to begin piecing parts together, trying to determine the ultimate shape and form, as well as an accurate taxonomic designation (botanical relationships).

The stumps were finally designated Eospermatopteris eriana and were shown to consist of three sections. There was a large central pith used for nutrient storage, a middle ring of vascular tissue — some areas being woody while others were not —and finally an outermost segment that was probably a root layer for providing stability for the tree base, which was essentially flat.

Meanwhile, identical crown materials had been collected in the mid-1900s in Belgium, Colorado and Venezuela. These remains were designated Wattieza givetiana, a cladoxylopsid which were once considered to be an ancestor of today’s ferns and horsetails (family Equisetaceae). However, it is now believed that this line was a dead-end evolutionarily.

These were spore-producing plants vaguely reminiscent in appearance of palm tree representations in ancient Egyptian art, although scientists describe the leaves “as fronds with branchelets that resemble a bottlebrush.”

Finally, in 2007, the puzzle pieces finally fit together. William Stein uncovered new finds from the northwest slope of South Mountain (also in Schoharie County), approximately eight miles east of the original finds. Interestingly, James Boyer had studied under William Stein.

The new finds were of two tree specimens, the first having a Wattieza crown attached to a long length of trunk showing many branches in the upper reaches and none in the lower sections. However, on the lower sections, there were branch scars that become increasingly indistinct as the trunk approached the base. The second specimen showed most of a trunk resembling the first specimen. However, this trunk was connected to an Eospermatopteris base.

Thus, a complete picture of the entire tree — which may have reached 26 feet — finally emerged. However, given that some of the stumps at Gilboa are twice the diameter of the 2007 finds, it is conceivable that many Eospermatopteris eriana were, in fact, much taller.

As to the question of the type of growing environment, this question is perhaps best resolved by further analysis of the sedimentary soil rather than by analogy with modern swamp-inhabiting plants.

No tree lives in splendid isolation. What else lived in Gilboa?

 

Have a thought or comment for Sura Jeselsohn? Email her at greenscenesura@gmail.com.

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