![]() ![]() 20 plants now reside in the collections of the Indiana University. It was written by Merton Young, a prolific collector whose entire collection of Chieftain No. The following article appeared in the March-April 1967 issue of Earth Science magazine. The fossils found there included many of the same plants and animals as those found in the Mazon Creek biota. The age of the Chieftain No 20 deposit is around 305.5 million years old, which is a little younger than the Mazon Creek deposits at about 307 million years ago, while the Stanley Cemetery Flora is older at about 313 million years ago. 20 Flora of the Dugger Formation in Vigo County Indiana and the Stanley Cemetery Flora of the Brazil Formation of both Vigo and Green Counties in Indiana. There were actually two distinct localities in the area. ![]() Although there is a pretty rich history of these fossils, there's not much reference information about the locality. What's your favorite Mazon Creek fossil? Tell us at there has been a few questions about the Mazon Creek-like fossils from around Terre Haute, Indiana. ![]() You can find out more in the new ESCONI plant book A Comprehensive Guide to the Fossil Flora of Mazon Creek, Jack Wittry 2020. This post wouldn't be complete with out a few photos of specimens. Some authors still believe that Callipteridium is the correct genus for this form. sullivantii were that they both have midveins that enter the pinnule toward the acroscopic side and basal pinnules that are very constricted at their bases. sullivantii His reasons for retaining both forms under A. White commented on these discrepancies, but chose to retain both forms under A. What separates them, is that the common form has a midvein that terminates abruptly near the middle of the pinnule (this agrees with Lesquereux's original description) and pinnules that are inflated, compared with the rarer form, which has a mid- vein extending to near the tip and rather flat pinnules. 1 form is commonly found in the Mazon Creek flora, while the Fig. This taxon has two forms, shown here as Fig. REMARKS: Alethopteris sullivantii is common. The lateral veins are thin, oblique, widely spaced and usually fork twice, often three times, then reach the margin at angles between 60° and 80 at a count of about 25 veins per centimeter. 5) in other cases it extends to nearly the pinnule apex where it branches into oblique lateral veins as in Fig. It sometimes rapidly terminates about half-way up the pinnule, dissolving into repeatedly branching veinlets (see Fig. The venation consists ofa strong, mostly straight and sometimes slightly decurrent midvein, that often appears to enter the pinnule towards the acroscopic side. They are widest two thirds of the way up towards the broadly rounded apex and are generally confluent at the bases, becoming less so near the pinna base where they become constricted (see circled portion of Fig. The pinnules are robust, oblique and often inflated. The rachis appears strong and irregularly striate. 134ĭESCRIPTION: The pinnae are large, linear-lanceolate, slightly narrowed at their bases and terminate in an oval pinnule. Alethopteris sullivanti (Lesquereux) Shimper. Callipteridium sulivanti (Lesquereux) Weiss. Callipteridium sulivanti (lLesquereux) Weiss. The text from "The Mazon Creek Fossil Flora" by Jack Wittry gives a complete history of its name and useful information to help with identification.Īlethopteris sullivantii (Lesquereux) Shimper, 1869 Here the art work is by Don Auler, who was President of ESCONI in the 1980s. sullivantii is a fairly common and was included in "The Keys To Identify Pennsylvanian Fossil Plants of the Mazon Creek Area". Specimens are usually 3 dimensional and can be quite striking. They first show up in the fossil record during the late Devonian. sullivantii is a seed fern ( Pteridospermatophyta), which is a group of plants that went extinct during the late Cretaceous Period. What's your favorite Mazon Creek fossil? Tell us at we look at one of my favorite Mazon Creek plants. ![]()
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