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This is the "Fossil Friday" post #17. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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What's your favorite Mazon Creek plant fossil? Tell us at email:[email protected].
Here is a common favorite, Alethopteris serlii.
This is Throwback Thursday #18. In these, we look back into the past at ESCONI specifically and Earth Science in general. If you have any contributions, (science, pictures, stories, etc ...), please sent them to [email protected]. Thanks!
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Here are some pictures from a field trip to Galena, IL that was held from August 8th to 9th, 1959. The cars in the background are really nice. Is that someone's Nash?. Field trips were a huge family affair. There are multiple early ESCONI notables in these photos. John Ade would be president in the 1960s and his son Dick is there long before he became president of ESCONI. There is Howard Knight a founding member and George Malotte of Esconi Associates, who published the Langford books. Violet Sobolik, who was the wife of Tony Sobolik, both were very active in ESCONI in the 1950s and 1960s. Doc Hoff, who was the president of ESCONI at that time, is in a couple photos.
They stayed at the DeSoto Hotel in Galena, which is still there. There was dinner and a song session.
Group shot
Old cars!
Dorothy Ade and Violet Sobolik
Howard Knight
George & Ethel Malotte.
Dick Ade
Dorothy and John Ade
What?!? High heels to collect rocks?
Doc Hoff, president of ESCONI in 1959
Harry Nelson
Doc Hoff at hotel after dinner
Song session at the DeSoto Hotel
ILLUSTRATION: ELENA LACEY
Wired has an informative article about how to outrun a dinosaur. It goes to the heart of the issue... allometry, which is the study of the relationship of body size to shape, anatomy, physiology and ultimately behavior. And, partial spoiler, we'd probably be safer than you think against the likes of T-rex and similarly sized meat eaters. I'm reminded of the movie "In-Laws" from 1979 with Peter Falk, when he yells "Serpentine, Serpentine!"
IF A MOUSE fell down a 1,000-foot mine shaft, the renowned evolutionary biologist JBS Haldane once proposed, the mouse would rise, shake the dust off itself, and scurry away. Maybe even right back up to do it again.
If a rat fell from the same height, however, it would die.
A human would break, Haldane writes, and a horse would splash.
Haldane does not provide a colorful verb in his 1926 essay On Being the Right Size for what would occur if a 9-ton Tyrannosaurus rex fell into that mine. But the giant predator would scream down the shaft at 172 mph, hit the ground with 120 tons of force and … shatter? Dismember? Detonate? Erupt?
Regardless, the purpose of Haldane’s gruesome thought experiment is to demonstrate the dramatically different relationship large animals have with gravity compared to smaller ones. This relationship, and the differing fates of the mouse and rat, are explained by the "square-cube" law, which is the simple idea that as an object expands, its volume cubes while its surface area merely squares. Because an animal’s surface area provides the brakes when falling, and its mass determines the force of its impact, the falls of various species can be either thrilling, tragic, or messy, depending on seemingly small differences in their size. It may be a simple concept—but because the law involves such rapid growth, it’s exceedingly difficult to intuit its occasionally dramatic effects. That’s particularly true with regards to the largest land animals to have ever walked the earth, and particularly important if you had to outrun them.
This is Mazon Monday post #18.
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Book inscriptions were much more common in the past. As owner of a book, which was a valuable possession. you might add your name to the inner cover. A recent Langford purchase by ESCONI member Roy Plotnick, reminded us of the historical significance of these inscriptions. Many of the books are signed by George. Please check your Langford books and send us anything interesting you might find.
This is Roy's book. It was presented to Mr. and Mrs. Lester Cunningham for a presentation they did on February 10th, 1961.
And, here is information about their presentation.
Dave Carlson has a copy that seems to have been owned by the first president of ESCONI, Bill Allaway!
Jack Wittry has John McLuckie's copy!
Here is a book that was owned at one time by Jim Konecny. I think I've seen at least two with his sticker.
One of the ESCONI gold editions has this note from George in 1958.
Another set of gold books were donated by Esconi Associates, who published the books.
Send us your inscriptions! We'd like to post more of them. Thanks!
This is the "Fossil Friday" post #16. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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Plant fossils with insect damage are fairly common in Mazon Creek, especially Macroneuropteris. It gives clues of behavior, which is typically rare in the fossil record. Here is a paper on this subject. Now... on to some examples... three leaves and a chunk of wood.
This is Throwback Thursday #17. In these, we look back into the past at ESCONI specifically and Earth Science in general. If you have any contributions, (science, pictures, stories, etc ...), please sent them to [email protected]. Thanks!
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Here are some ESCONI patches and logos through the years. The first few date to the 1960s.
This one dates to the 1980s and was sent by John Liskey. Dave Liskey is his father and was the Junior Study Group Leader in the 1980s.
Found in the warehouse. Most likely pre-1980.
Irene Broede's trilobite pin!
I think that is the trilobite that Rob Sula created... 1990s or 2000s?
Messenger bags... again Rob Sula's trilobite
Hats from the 2010s. Care of Keith Robitschek
image: Davide Bonadonna
Palaeocast has an episode on the extinction of the dinosaurs. The episode is an interview with Dr Alessandro Chiarenza about some very thorough analysis that compares the Chicxulub asteroid event with the volcanic eruptions at the Deccan Traps. The paper detailing this analysis can be found in the journal Proceedings of the National Academy of Sciences.
The end-Cretaceous (or K-Pg) extinction is one of the best known mass extinctions in Earth’s history, primarily because that is when non-avian dinosaurs disappeared. Although the popular idea is that an asteroid impact was what caused the extinction, the science hasn’t actually been that clear. More recently, a second hypothesis has challenged the idea asteroid as the main culprit, suggesting that huge volcanic eruptions in what is now India called the Deccan Traps was responsible. It has also been suggested that dinosaurs were already in decline when these things happened, speeding up the inevitable.
In this interview, we speak with Dr Alessandro Chiarenza, a research associate at University College London about his new paper published today in PNAS showing that it really was the asteroid impact that killed the dinosaurs. This new study, based on research he did during his PhD at Imperial College London, uses a large amount of data put into climatic models to analyse different scenarios caused by an asteroid impact, the Deccan Traps volcanism, and a combination of the two. This study showed that the asteroid caused a prolonged impact winter, causing the extinction of the dinosaurs.
Slabs at the excavation site in western Utah with circles indicating the locations of Elrathia kingii fossils, some of which can be as small as half a millimeter long. Credit: M. Hopkins/AMNH
Phys.org has an article about probably the most common trilobites, Elrathia kingii. The article is about new research that used this trilobite to understand the ontogeny of this iconic species. The research can be found in a paper in the journal Papers in Palaeontology.
If you've ever held a trilobite fossil, seen one in a classroom, or walked by one in a store, chances are it was Elrathia kingii, one of the most common and well-recognized trilobites, and collected by the hundreds of thousands in western Utah. But despite the popularity of this species, scientists had not determined how it grew—from hatchling to juvenile to adult—until now. New work from the American Museum of Natural History published today in the journal Papers in Palaeontology describes the development and growth rate of Elrathia kingii—only the second such dataset to be compiled for a trilobite—allowing for the first comparison among trilobite species.
"There's quite a big size range among trilobites. Some never got bigger than about a centimeter, while the largest on record is 72 centimeters (28 inches)," said Melanie Hopkins, an associate curator in the Museum's Division of Paleontology and the study's author. "Growth-rate studies like this one can help us tackle some of the big-picture questions: How did some trilobites get so big? What was the environmental context for that? And how did body size evolve over the evolutionary history of the clade?"
Trilobites are a group of extinct marine arthropods—distantly related to the horseshoe crab—that lived for almost 300 million years. They were incredibly diverse, with more than 20,000 described species. Their fossilized exoskeletons are preserved in sites all over the world, from the United States to China. Like insects, they molted throughout their lifetimes, leaving clues to how they changed during development. But to calculate the species' growth rate, scientists need fossils representing all stages of the animal's life—and lots of them.
This is Mazon Monday post #17.
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Acanthodes sp.
There are a few types of fish known in the Mazon Creek biota. And while, the classification has changed since the creature corner article on fish, which appeared in March 1989. It's still interesting and instructive. Here is the text and a few drawings.
A recent discussion into the classification of Mazon Creek fishes proved so interesting it is hoped that you, the reader, might find it equally so. Mazon Creek strata is Middle Pennsylvanian (Westphalian D) in age. "Modern" fish had not yet appeared upon the scene. As an aid in keeping this article from becoming over long, species names will be omitted.
All fish are divided into two basic groups -jawless fishes and jawed fishes. Jawless fishes (hagfisties and lampreys) are placed in the Class Agnatha.
Agnatha found in the Mazon Creek biota consists of: Mazomyzon, Pipiscius and Gilpichthys.
Jawed fishes are placed in the Superclass Pisces-Gnathostomata. This grouping is then further divided into three classes:
The Chondrichthyans of the Mazon Creek biota are: Bandringa, Dabascacanthus, Similharriota, and 8 more common genera.
The Acanthodians of Mazon Creek are: Acanthodes and Gyracanthus.
Now to keep things interesting, the Class Osteichthyes is divided into two subclasses: Actinopterygii (ray-finned fishes) whose modern representatives, the teleosts, are the common fishes of today. The remaining bony fishes are placed in the Sarcopterygii (fleshy-finned fishes), a group heading for extinction, although their ancient representatives are considered to be the ancestors of land vertebrates.
The species of the Actinopterygii present in Mazon Creek concretions are: Chirodus, Elonichthys, Palaeoniscoids, Pyritocephalus, Palaeophichthys, Platysomus and Haplolepis.
The Subclass Sarcopterygii is divided into two component groups: Crossopterygii (\obe-finned fishes or coelacanths) which are the ancestors of tetrapods and the Dipnoi (lungfish) whose large scales are found at Mazon Creek/Pit 11.
The species of the Order Crossopterygii found in the Mazon Creek biota are: Megalichthys, Rhizodopsis and Rhabdoderma.
Lastly, the order Dipnoi: Conchopoma, Ctenodus and Megapleuron.
Concretions containing well-preserved fishes are uncommon -much sought after by the scientific community. Many of the genera mentioned above are "firsts" and have vastly expanded our knowledge of vertebrate evolution.
Lest you think the listing above is "set in stone", classification (taxonomy) is a rigorous discipline, not for the unwary. One's pronouncements often engender heated discussions. To quote an old poet:
"Who didst with Pitfall and with Gin
beset the road that I was in."
Or so it seems at times.
- Andrew A. Hay
The following two concretions are Esconichthys, sometimes referred to as the bladei. At times in the past, it was classified as a larval amphibian. Some now consider it as a larval fish. Although, it's classification is open to further research.
The next one is an awesome Rhabdoderma, which is a coelacanth. This specimen and its modeled likeness was provided by David Duck. Soft tissue is so seldom preserved in the fossil record, and that's what makes this specimen so special. If you look closely, you can see its eggsac preserved three dimensionally. The model reconstruction is to 1:1 scale. Dave has been constructing models for quite a while. They are very detailed. See this post for more information and a picture of his Acanthodes.
LiveScience has a story about a cousin to both dinosaurs and pterosaurs. Kongonaphon kely, meaning "tiny bug slayer", lived about 237 million years ago, during the Triassic period, in what is now Madagascar. It was discovered in 1998, but just recently described in a paper that appeared in the journal Proceedings of the National Academy of Sciences.
The pipsqueak's fossils were discovered in the Morondava Basin of southwestern Madagascar in 1998 by a group of researchers, led by study co-researcher John Flynn, the Frick Curator of Fossil Mammals at the American Museum of Natural History (AMNH) in New York City (at the time Flynn worked at the Field Museum in Chicago). An analysis of its anatomy revealed that K. kely belongs to the scientific clade called Ornithodira, whose members are the last common ancestors of the dinosaurs and pterosaurs and their descendants.
The early Ornithodira, however, are poorly known, because there are few known specimens like K. kely that date to the beginning of this lineage.
"It took some time before we could focus on these bones, but once we did, it was clear we had something unique and worth a closer look," Flynn said.
K. kely is one of the smallest non-avian ornithodirans on record. Other known early Ornithodira specimens are also small, but previously these critters were thought to be "isolated exceptions to the rule," Kammerer said.
This is the "Fossil Friday" post #15. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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On Tuesday, we had a post about the "Last Trilobites". The Phillipsiidae was one of the trilobite families that made it through to the Permian in Kansas. Ameura and Ditomopyge are small species that cane be found in the rocks of the Flint Hills in northeastern Kansas. Complete specimens are fairly rare, but pygidiums are not uncommon.
Here are some specimens including some enrolled examples, although they are more flattened than rolled.
This is Throwback Thursday #16. In these, we look back into the past at ESCONI specifically and Earth Science in general. If you have any contributions, (science, pictures, stories, etc ...), please sent them to [email protected]. Thanks!
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Membership dues in 1953 were $2 for an active member and 75 cents for a junior member. If you were a non-resident it was $1.25. For non-resident, the thinking was you would receive the bulletin, but wouldn't attend meetings and field trips. Dues were pro-rated based on when you joined. If you use 5% interest and project those dues forward 67 years, that $2 becomes $131.42. At 8%, it would be $210.27. Currently, dues are $20 per year. So, if you didn't know it... ESCONI dues are a bargain! Please join, we are a club of friendly people that have interesting meetings with stimulating conversations, an informative bulletin, and exciting field trips to collect awesome specimens!
Researchers trekked into Siberia to find hard evidence that the Permian-Triassic extinction was the consequence of explosive volcanic eruptions and the ensuing global warming.COURTESY OF LINDY ELKINS-TANTON
Wired has an article about research into the Permian-Triassic mass extinction event, which happened about 250 million years ago. Sometimes called "The Great Dying", this event, which was really a series of events, took out about 70% of land species and more than 95% of marine species. The current theory about its cause is a runaway greenhouse driven by massive volcanic eruptions in what is now Siberia. The article is the story of Planetary scientist Lindy Elkins-Tantyon's mission to find real hard evidence to prove it.
SOME 250 MILLION years ago, the organisms of Earth were having a very bad time—the very worst time, you might say. The Permian-Triassic extinction event was unfolding, in which 70 percent of land species and 96 percent of marine species disappeared. Runaway global warming had raised equatorial ocean temperatures to 104 degrees Fahrenheit. The seas rapidly acidified, so shelled critters struggled to build their protective homes. Indeed, the fossil record shows these species got it the worst—strong evidence that the extinction’s culprit was CO2 mucking with the oceans’ pH balance, and the rest of the planet, for that matter. Every decade or so, ozone-eating gases would dissolve Earth’s protective layer in the sky, irradiating plants and animals, before the ozone layer closed up. This happened again and again, allowing periodic blasts of extreme radiation to bombard the planet.
One long-standing hypothesis for the cause of the Permian-Triassic extinction, also known as the Great Dying, will sound worryingly familiar to us modern humans: the large-scale burning of coal. Only such a catastrophe, scientists reckoned, had the power to transform Earth so radically in such a short period of time; the fossil record indicates that species weren’t dying off en masse over millions of years, or hundreds of thousands of years, but tens of thousands of years. A carbon-spewing volcanic event alone—even the biggest of booms—couldn’t explain such a cataclysm. And there’s no evidence of an asteroid strike in this period, like the one that would kill off the dinosaurs 190 million years later.
It’s a juicy theory. The only problem is that scientists didn’t have the hard evidence to prove a massive combustion of coal did all those species in. But they knew where to look: in what we now call Siberia, a frigid expanse of land that 250 million years ago was anything but chilly, because it was flooded with lava. Volcanoes pumped out so much planetary goop that the stuff could have covered the entire continental United States a half-mile deep. And unfortunately for all life on Earth, scientists suspected, the lava was flash-incinerating vast deposits of coal and ejecting massive quantities of greenhouse gases into the atmosphere.
That’s how the theory goes, anyway.
This is Trilobite Tuesday post #15.
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Both the American Museum of Natural History and Trilobites.info have pages on "The Last Trilobites". By the end of the Permian, trilobites had existed for nearly 300 million years. That stretch of time spread from the lower Cambrian to the mass extinction events at the end of the Permian. Their highest diversity was during the Ordovician. After that, they endured through multiple mass extinction events. Their diversity had dwindled by the end, with only a few families still around. It was the Permian mass extinction that took them out, along with more than 90% of all life on Earth at that time.
The AMNH's page on the last trilobites has a nice write up and some pictures.
At 5 cm, Pudoproetus fernglenensis was large for a Mississippian trilobite.
The Pennsylvanian-age proetid, Ameura major, was fossilized in a distinctive white calcite.
Witrydes rosmerta, found in Belgium, displays the classic proetid shape.
The last trilobites, those of the proetid order that lived during the Mississippian, Pennsylvanian and Permian periods, were certainly not the biggest, baddest or boldest examples of their class. Yet even considering their diminutive size (usually an inch of less) and their modest, generally ovate body plan -- a design that allowed them to burrow beneath the sea floor mud in order to avoid the constant threat of predation -- these trilobites still contributed significantly to their kind's lingering legacy. They may have been a far cry from the foot-long, spinose trilobite “monsters” that inhabited the Ordovician and Silurian seas, but in look, design and lifestyle they were still very much quintessential trilobites.
The fossilized evidence of these last trilobites can be found in numerous spots across the face of the planet. The 360 million year old Mississippian-age outposts of Missouri, for example, have long been a favorite of collectors in search of such species as Ameropiltonia lauradanae and Comptonaspis swallowi. Over the last two decades, New Mexico has also emerged as a Mississippian hotspot, where 23 species have now been scientifically identified from the Caballero and Lake Valley formations, including the likes of Piltonia carlakertisae, Namuropyge newmexicoensis and Pudoproetus fernglenensis. These trilobites are often preserved in a dark brown or black calcite which contrasts dramatically against a reddish-pink matrix. Another important Mississippian-age trilobite location can be found in Antoing, Belgium, where for more than a century, well-preserved examples of such species as Piltonia kuehnei, Witrydes rosmerta and Bollandia globiceps have been found in the hard black mudstone rocks of the area. At the start of the Pennsylvanian, roughly 323 million years ago, trilobites were clearly continuing their decline in the fossil record, yet the proetid order still managed to produce an interesting array of species including such notable American varieties as Ditomopyge olsoni, Ameua major and the highly pustulated Brachymetopus nodusus. In recent years, a number of species from the remote Ulutau mountains region of Kazakhstan have invaded the world market, with many of these dolomitic specimens (including Ditomopyge kumpani and Griffithides praepermicus)being fossilized along-side other fauna, including brachiopods and crinoids, providing an interesting view of life at this stage of the evolutionary game.
Trilobites.info has a table of the last genus and when they are thought to go extinct.
Although the Trilobita went entirely extinct at the end of the Permian (251 million years ago [mya]), when >90% of all species on the planet were extinguished, the pattern of decline for trilobites had been significant since the end of the Ordovocian. By the end of the Devonian (359 mya), the last of the Phacopidae went extinct, ending the order Phacopida. All of the orders of trilobites had gone extinct, except for one: the Proetida. This order persisted into the Carboniferous (with two superfamilies represented: Aulacopleuroidea and Proetoidea. There was even a major adaptive radiation among the family Phillipsiidae (especially various subfamilies such as Phillipsiinae and Ditomopyginae) in the early Carboniferous, as changes in the world's continents created expanding habitat opportunities. But the number of taxa fell dramatically after the Mid-Carboniferous, and by the start of the Permian (299 mya), only the families Brachymetopidae, Phillipsiidae, and Proetidae remained. The table below lists all of the trilobite genera that existed in the Permian, and indicates when these genera became extinct.
And, they address a theory on what the last species was.
Owens (2003) reviewed the last trilobites to go extinct during the Permian, and revealed that five genera of trilobites persisted until the great extinction crisis at the end of the Permian. This event was perhaps the largest extinction event in Earth's history, wherein >90% of all species were extinguished. However, the fossil record reveals that for trilobites, there were two crises during the Permian, one during the Middle Permian (266 million years ago, in the Late Guadalupian Epoch), in which over half of the trilobite genera extant at the time were lost (see the numerous "Middle Permian" extinctions in the table above). Of those that remained, only five persisted to the end Permian event: Cheiropyge (an aulacopleuroid in the family Brachymetopidae), Kathwaia (a proetoid in the family Phillipsiidae, subfamily Bollandiinae), Paraphillipsia (Phillipsiidae, Cummingellinae), Acropyge (Phillipsiidae, Ditomopyginae), and Pseudophillipsia (also Ditomopyginae). Specimens of these genera are shown at right: These are the last genera of the trilobites, and are found in various localities today including Pakistan, China, Russia, Hungary, and Japan.
Reconstructions of three of these Permian trilobite species are presented at bottom right: Leftmost: Cheiropyge koizumii (Japan, Brachymetopidae); Middle: Pseudophillipsia sumatrensis (Malaysia, Proetidae); Far right: Paraphillipsia karpinskyii (Ukraine, Proetidae)
This is Mazon Monday post #16.
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A particularly well-preserved and only partly compressed specimen of Adelophthalmus mazonensis (Meek and Worthen) from the Herdina collection (H-3); × 1.8. The ocellar mound and the short genal spines of the carapace are particularly well preserved.
Found by Eugene Richardson & George Langford; see State of Illinois Scientific Papers Vol. III, No.4, 1948.
Maybe it's their size (early Devonian species could be almost three meters long!) or their similarity to scorpions (they're called sea-scorpions) or their rarity (they are fairly scarce in the fossil record), it's hard to say why, but Eurypterids were fascinating animals. There is currently only one known Mazon Creek species - Adelophthalmus mazonensis. It wasn't very large... maybe a couple inches. But, it is very rare!
George Langford had an entry for Adelophthalmus mazonensis. It can be found here.
Here is the text of the Creature Corner article from September 1988.
Adelophthalmus mazonensis ( eurypterid)
Adelophthalmus mazonensis, previously described under the names of Anthraconectetes mazonensis, Eurypterus mazonensis, Eurypterus (Anthraconecetes) mazonensis and Lepidoderma mazonense, was an eurypterid. It is a member of the Braidwood fauna and of the Mazon Creek Biota.
Eurypterids appear in the fossil record during the Ordovician, reaching their maximum diversity in the Silurian, with some species reaching lengths of 8 to 9 feet. Eurypterid extinction occurred during the Permian, additional victims of the great Permian die-off. During the early Paleozoic, eurypterids were marine animals; by the later Paleozoic they had become inhabitants of the coastal plains, deltas and inshore lagoons adjacent to the seemingly continuous tropical coal swamps. Eurypterids had become the dwellers of brackish to freshwater environments.
Meek and Worthen (1868) described the first eurypterid found in a Mazon Creek concretion, naming it Eurypterus (Anthraconecetes) mazonensis. Yet they made mention of a "very similar" type from Bohemia with the generic name Adelopthalmus. It is always a source of wonder to study Meek and Worthen's original publications. Their works of the last century describe and name fossils that prove to be extremely rare. In many cases ten's of years elapsed before another of the same species was discovered.
Eyrypterids are arthropodous, crustacea-like animals, close relatives of horseshoe crabs, spiders and scorpions. A long rapidly tapering body bears the cephalothorax; a prosoma consisting of a fused head and thorax. The abdomen is ringed by twelve segments, ending in a long tail spine (telson). The prosoma bore two pairs of eyes and six pairs of appendages ("legs") that are progressively longer rearwards. The first pair is the shortest, is chelate (pincer-like) and is located ahead of the mouth (pre-oral), followed by four pairs of walking legs. The last is the longest and is a pair of paddle-like swimming legs. A. mazonensis possessed a small triangular spine on the prosoma, plus spines at the rear of the abdominal segments. Its width was slightly more than 2 inches and its length minus the telson was approximately 6 inches. Complete specimens of Adelophthalmus are extremely rare. Abdominal segments, a prosoma, or an appendage are the "eurypterids" most often found. The body structure denotes an active predator well equipped for a predatorial life in lagoons, marshes and coal swamps. Small fish, amphibians, insects, and perhaps a little cannibalism are assumed for the diet.
In 1966 the late Dr. E. S. Richardson Jr. published "A Tentative Check List of Validly Described Species from the Mazon Creek Faunas". It listed three eurypterids, Adelophthalmus mazonensis, Mazonipterus cyclophthalmus and Mycterops sp. The most recent paper on our subject (now in preparation) takes note that Mycterops sp. Is questionable, being known only from isolated pieces. Author (R. Plotkin) further comments that Richardson, after more research, discarded Mazonipterus c. as a valid species. The described specimen proved to be a leaf scar, a plant fragment; not a prosoma. That leaves our Creature as the eurypterid of the Mazon Creek Biota.
Our Creature is a member of the Phylum: Cheliceriformes; Class Merostomata; Subclass Eurypterida; Genus Adelophthalmus; Species mazonensis.
Found by John M. McLuckie.
Found by George Langford in 1949.
Found by Eugene Richardson & GL; see State of Illinois Scientific Papers Vol. III, No.4, 1948.
Wann Langston, Jr., at UC, Berkeley, supervises the reconstruction of the first skeleton of Dilophosaurus in the early 1950s. TEXAS VERTEBRATE PALEONTOLOGY COLLECTIONS
National Geographic has a post about the "best worst-known" dinosaur - Dilophosaurus. Adam Marsh, a paleontologist at the Petrified Forest National Park in Arizona, led an effort to redescribe Dilophosaurus. That paper was published recently in the Journal of Paleontology.
Now, the new analysis includes two previously unstudied fossil specimens from Arizona, providing the first clear picture of what Dilophosaurus was like in life. Rather than a small dinosaur that relied on gimmicks such as venom and a neck frill to subdue its prey, Dilophosaurus was a powerful predator and one of the largest land animals in North America when it lived during the early Jurassic period, which lasted from about 201 to 174 million years ago.
“It’s a lot bigger than people would think from watching Jurassic Park,” Marsh says.
A Navajo man named Jesse Williams found the first Dilophosaurus specimens in 1940 on Navajo Nation land near Tuba City, Arizona. In 1942, Williams showed the fossils to paleontologists at the University of California, Berkeley, including Samuel Welles, who named it as a new species in 1954.
The team that reconstructed the dinosaur for display used plaster versions of bones to fill in for missing fossils. The resulting dinosaur was “intentionally made to look like [the different predator] Allosaurus … because it was going on a wall mount and they wanted to make it look complete,” Marsh says. The trouble is that the 1954 study, and additional research that Welles published in 1984, didn’t make clear which bones were actual fossils and which were plaster parts.
Subsequent research based on these early papers led to confusion about whether Dilophosaurus was more closely related to turkey-size Triassic carnivores, such as Coelophysis, or larger late Jurassic species, such as Ceratosaurus and Allosaurus.
“It just wasn’t clear after 1984 if they were talking about real anatomy or something described from plaster,” Marsh says. Without anyone spending time and resources on further study, the muddled picture of the animal’s anatomy persisted for decades.
