This is Mazon Monday post #7. This is about one of the favorite Mazon animals, the Tully monster.
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A reconstruction of the Tully Monster as it would have looked 300 million years ago, swimming in the Carboniferous seas. Notice the jointed proboscis, the multiple rows of teeth, and the dorsal eye bar. Credit: Sean McMahon / Yale University
Phys.org has an article about some new research about the Tully Monster. The Tully Monster was first discovered by Francis Tully in 1955. He was fossil hunting in Pit 11 of the old Peabody Coal Company's strip mines near Braidwood, IL., when he came across a strange looking fossil. He brought the fossils to Eugene Richardson at the Field Museum, who had never seen anything like it. The animal was quickly dubbed "My Tully's Monster". In 1966, Richardson formally described it and gave it its proper scientific name... Tullymonstrum gregarium. Even though it was originally designated an invertebrate, No one knew exactly where it belonged on the tree of life.
In 2016, Victoria McCoy, along with a bunch of other researchers including Scott Lidgard and Paul Mayer of the Field Museum, coauthored a paper called simply "The 'Tully Monster' is a vertebrate". The study detailed in that paper analyzed 1200 specimens. Looking at eyes, teeth, gills, ... literally the whole body and found enough evidence to place it with lampreys.
Abstract
Problematic fossils, extinct taxa of enigmatic morphology that cannot be assigned to a known major group, were once a major issue in palaeontology. A long-favoured solution to the ‘problem of the problematica’1, particularly the ‘weird wonders’2 of the Cambrian Burgess Shale, was to consider them representatives of extinct phyla. A combination of new evidence and modern approaches to phylogenetic analysis has now resolved the affinities of most of these forms. Perhaps the most notable exception is Tullimonstrum gregarium3, popularly known as the Tully monster, a large soft-bodied organism from the late Carboniferous Mazon Creek biota (approximately 309–307 million years ago) of Illinois, USA, which was designated the official state fossil of Illinois in 1989. Its phylogenetic position has remained uncertain and it has been compared with nemerteans4,5, polychaetes4, gastropods4, conodonts6, and the stem arthropod Opabinia4. Here we review the morphology of Tullimonstrum based on an analysis of more than 1,200 specimens. We find that the anterior proboscis ends in a buccal apparatus containing teeth, the eyes project laterally on a long rigid bar, and the elongate segmented body bears a caudal fin with dorsal and ventral lobes3,4,5,6. We describe new evidence for a notochord, cartilaginous arcualia, gill pouches, articulations within the proboscis, and multiple tooth rows adjacent to the mouth. This combination of characters, supported by phylogenetic analysis, identifies Tullimonstrum as a vertebrate, and places it on the stem lineage to lampreys (Petromyzontida). In addition to increasing the known morphological disparity of extinct lampreys7,8,9, a chordate affinity for T. gregarium resolves the nature of a soft-bodied fossil which has been debated for more than 50 years.
Now in 2020, the new paper looks at chemical signatures of soft tissues in the fossils to provide further evidence that the 'Tully Monster' is indeed a vertebrate.
Abstract
The chemical composition of fossil soft tissues is a potentially powerful and yet underutilized tool for elucidating the affinity of problematic fossil organisms. In some cases, it has proven difficult to assign a problematic fossil even to the invertebrates or vertebrates (more generally chordates) based on often incompletely preserved morphology alone, and chemical composition may help to resolve such questions. Here, we use in situ Raman microspectroscopy to investigate the chemistry of a diverse array of invertebrate and vertebrate fossils from the Pennsylvanian Mazon Creek Lagerstätte of Illinois, and we generate a ChemoSpace through principal component analysis (PCA) of the in situ Raman spectra. Invertebrate soft tissues characterized by chitin (polysaccharide) fossilization products and vertebrate soft tissues characterized by protein fossilization products plot in completely separate, non‐overlapping regions of the ChemoSpace, demonstrating the utility of certain soft tissue molecular signatures as biomarkers for the original soft tissue composition of fossil organisms. The controversial problematicum Tullimonstrum, known as the Tully Monster, groups with the vertebrates, providing strong evidence of a vertebrate rather than invertebrate affinity.
