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50-737: It is alternately considered its own geologic formation (as the Coon Creek Formation) or a distinct member of the wider Ripley Formation (as the Coon Creek Member or the Coon Creek Tongue). Geologists employ biostratigraphy , the use of index fossils, for dating sedimentary rock units like the Coon Creek. Index fossils are species of plants or animals that existed over a wide area for a geologically short period of time . The cephalopod Jeletzkytes nodosus

100-600: A phalanx . Although most of the Trachodon teeth turned out to belong to ceratopsids , the holotype and remains of T. occidentalis would come to be recognized as the first recognized hadrosaur specimens. Around the same time in Philadelphia , on the other side of the continent, geologist William Parker Foulke was informed of numerous large bones accidentally uncovered by farmer John E. Hopkins some twenty years earlier. Foulke obtained permission to investigate

150-533: A century to come. Further discoveries such as " Hadrosaurus minor " and " Ornithotarsus immanis " would come from the East, and Edward Drinker Cope led an expedition to the Judith River Formation where Trachodon was found. Upon the fragments discovered he named seven new species in two genera, as well as assigning material to Hadrosaurus . Cope had studied the jaws of hadrosaurs and come to

200-484: A formation in another region and a formation may reduce in rank for member or bed as it "pinches out". A bed is a lithologically distinct layer within a member or formation and is the smallest recognisable stratigraphic unit. These are not normally named, but may be in the case of a marker horizon . A member is a named lithologically distinct part of a formation. Not all formations are subdivided in this way and even where they are recognized, they may only form part of

250-573: A full revision of the group as part of his Graduate studies through the 1970s and 1980s. John R. Horner would also begin to leave his impact on the field, including with the naming of Maiasaura in 1979. Hadrosaur research experienced a surge in the decade of the 2000s, similar to the research of other dinosaurs. In response to this, the Royal Ontario Museum and the Royal Tyrrell Museum collaborated to arrange

300-681: A representative sample of the fossils. • There is a rich diversity of animals with over 600 different species of organisms found. • Because the Coon Creek Formation sediment is unconsolidated, it makes it very easy to collect and prepare the fossils. Member (geology) A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic , lithologic or paleontologic features ( facies ) that characterize it. Units must be mappable and distinct from one another, but

350-574: A similar body layout. Hadrosaurs were among the most dominant herbivores during the Late Cretaceous in Asia and North America, and during the close of the Cretaceous several lineages dispersed into Europe, Africa, and South America. Like other ornithischians , hadrosaurids had a predentary bone and a pubic bone which was positioned backwards in the pelvis. Unlike more primitive iguanodonts,

400-465: A similar project decades later. Eventually they realized the whole of Ornithopoda was too broad of a scope, until eventually it was narrowed down to specifically North American hadrosaurs. Their monograph, Hadrosaurian Dinosaurs of North America , was published in 1942, and looked back at the whole of understanding about the family. It was designed as a definitive work, covering all aspects of their biology and evolution, and as part of it every known species

450-738: Is a set of two or more associated groups and/or formations that share certain lithological characteristics. A supergroup may be made up of different groups in different geographical areas. A sequence of fossil -bearing sedimentary rocks can be subdivided on the basis of the occurrence of particular fossil taxa . A unit defined in this way is known as a biostratigraphic unit, generally shortened to biozone . The five commonly used types of biozone are assemblage, range, abundance, interval and lineage zones. Hadrosaur Hadrosaurids (from Ancient Greek ἁδρός ( hadrós )  'stout, thick' and σαύρα ( saúra )  'lizard'), or duck-billed dinosaurs , are members of

500-563: Is a set of two or more formations that share certain lithological characteristics. A group may be made up of different formations in different geographical areas and individual formations may appear in more than one group. Groups are occasionally divided into subgroups, but subgroups are not mentioned in the North American Stratigraphic Code, and are permitted under International Commission on Stratigraphy guidelines only in exceptional circumstances. A supergroup

550-414: Is a time-sensitive fossil found in rocks a little younger than 70.6 million years old in the western United States. Other index fossils from Coon Creek date a little older than 70.6 million years. The overlap indicates that Coon Creek sediments were probably deposited between 70 and 71 million years ago. The Mississippi Embayment extends roughly north–south from central Mississippi to southern Illinois. It

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600-583: Is descended from the last common ancestor of Lambeosaurus and Saurolophus . Below is a cladogram from Prieto-Marquez et al. 2016. This cladogram is a recent modification of the original 2010 analysis, including more characters and taxa. The resulting cladistic tree of their analysis was resolved using Maximum-Parsimony. 61 hadrosauroid species were included, characterized for 273 morphological features: 189 for cranial features and 84 for postcranial features. When characters had multiple states that formed an evolutionary scheme, they were ordered to account for

650-595: The ICZN . Prieto-Márquez defined Hadrosaurinae as just the lineage containing H. foulkii , and used the name Saurolophinae instead for the traditional grouping. Hadrosauridae was first defined as a clade , by Forster, in a 1997 abstract, as simply "Lambeosaurinae plus Hadrosaurinae and their most recent common ancestor". In 1998, Paul Sereno defined the clade Hadrosauridae as the most inclusive possible group containing Saurolophus (a well-known saurolophine) and Parasaurolophus (a well-known lambeosaurine), later emending

700-570: The ornithischian family Hadrosauridae . This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includes genera such as Edmontosaurus and Parasaurolophus , was a common group of herbivores during the Late Cretaceous Period . Hadrosaurids are descendants of the Late Jurassic / Early Cretaceous iguanodontian dinosaurs and had

750-563: The American West would come to provide many very complete specimens that would form the backbone of hadrosaur research. One such specimen was the very complete AMNH 5060 (belonging to Edmontosaurus annectens ), recovered in 1908 by the fossil collector Charles Hazelius Sternberg and his three sons in Converse County, Wyoming . It was described by Henry Osborn in 1912, who dubbed it the "Dinosaur mummy". This specimen's skin

800-530: The Coon Creek Formation as well. Coon Creek is widely recognized as a konservat-lagerstatte for its exquisitely preserved specimens. Coon Creek has been named as one of the country's top twelve fossils sites for several reasons . • The fossils are found in their original state. The hard shells have not been permeated by groundwater and not replaced by minerals. • The number of fossils is stupendous. Many times you will literally find fossils on top of fossils. Most fossil sites require concentrated efforts to find

850-566: The Dinosaur Renaissance. Hadrosaurids likely originated in North America, before shortly dispersing into Asia. During the late Campanian - Maastrichtian , a saurolophine hadrosaurid migrated into South America from North America, giving rise to the clade Austrokritosauria , which is closely related to the tribe Kritosaurini . During the late early Maastrichtian, several lineages of Lambeosaurinae from Asia migrated into

900-500: The European Ibero-Armorican Island (what is now France and Spain), including Arenysaurini and Tsintaosaurini . One of these lineages later dispersed from Europe into North Africa, as evidenced by Ajnabia , a member of Arenysaurini. The family Hadrosauridae was first used by Edward Drinker Cope in 1869, then containing only Hadrosaurus . Since its creation, a major division has been recognized in

950-597: The International Hadrosaur Symposium, a professional meeting about ongoing hadrosaur research that was held at the latter institution on September 22 and 23 in 2011. Over fifty presentations were made at the event, thirty-six of which were later incorporated into a book, titled Hadrosaurs , published in 2015. The volume was brought together primarily by palaeontologists David A. Eberth and David C. Evans, and featured an afterword from John R. Horner , all of whom also contributed to one or more of

1000-478: The aralosaurins, tsintaosaurins, lambeosaurins and parasaurolophins, while saurolophines included the brachylophosaurins, kritosaurins, saurolophins and edmontosaurins. Hadrosaurids were facultative bipeds , with the young of some species walking mostly on two legs and the adults walking mostly on four. Ferdinand Vandeveer Hayden , during expeditions near the Judith River in 1854 through 1856, discovered

1050-426: The authors. Though they still proposed a diet of water plants, they considered it likely this would be supplemented by occasional forrays into browsing on land plants. Twenty years later, in 1964, another very important work would be published, this time by John H. Ostrom . It challenged the idea that hadrosaurs were semi-aquatic animals, which had been held since the work of Leidy back in the 1850s. This new approach

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1100-431: The bottom sediments. Periodic hurricanes may have brought in heavy loads of river sediment to bury the plants and animals living there. Conditions for life were ideal; the water was warm and of normal salinity . Wave action ensured sufficient oxygenation for animal life. The seafloor was heavily populated with shellfish , crabs , and lobsters . Huge plesiosaurs , marine crocodiles , sea turtles , and mosasaurs shared

1150-766: The conclusion that the teeth were fragile and could have been dislodged incredibly easily. As such, he supposed the animals must have fed largely on soft water plants; he presented this idea to the Philadelphia Academy in 1883, and this idea would come to be very influential on future study. Research would continue in the Judith River area for years to come, but the formation never yielded much more than fragmentary remains, and Cope's species as well as Trachodon itself would in time be seen as of doubtful validity . The Eastern states, too, would never yield particularly informative specimens. Instead, other sites in

1200-479: The contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Sequences of sedimentary and volcanic rocks are subdivided on the basis of their shared or associated lithology . Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank , higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank,

1250-485: The corrosive action of water and the hard parts of the clams, snails, crabs, and shrimps were well preserved. Occasionally the bones of vertebrates are found, as well as the cartilaginous vertebrae of sharks. Fish scales and plant leaves are sometimes found as well . The Coon Creek Formation has one of the highest densities of fossil in Eastern North America. Crustacean fossils have also been unearthed in

1300-438: The decaying wood. Plankton ate the bacteria. Clams filtered the small plankton. Snails ate the clams and were eaten in turn by crabs and fish. Mosasaurs and cephalopods ate the fish and crabs. Some organisms were swimmers or floaters, but most lived on or in the sandy mud of the sea bottom. This layer of sandy clay, bones, and shells became the Coon Creek Formation. As of 2016, the only known dinosaurs found in this region include

1350-422: The definition to include Hadrosaurus , the type genus of the family. According to Horner et al. (2004), Sereno's definition would place a few other well-known hadrosaurs (such as Telmatosaurus and Bactrosaurus ) outside the family, which led them to define the family to include Telmatosaurus by default. Prieto-Marquez reviewed the phylogeny of Hadrosauridae in 2010, including many taxa potentially within

1400-592: The east lay a marshy lowland bordering the limestone bluffs of the Western Highland Rim of the Nashville Basin, home to duckbill and theropod dinosaurs. Sluggish rivers annually washed tons of driftwood, along with the occasional dinosaur carcass, from this heavily forested area into the bay . The margins of the bay teemed with marine life. Crabs, snails, lobsters, clams, scallops, whelks, nautilus, sharks, and other familiar animals lived in

1450-639: The family. The family is now formally defined in the PhyloCode as "the smallest clade containing Hadrosaurus foulkii , Lambeosaurus lambei , and Saurolophus osborni ". The two main subfamilies of Lambeosaurinae and Saurolophinae belong to the clade Euhadrosauria (sometimes called Saurolophidae ), defined as "the smallest clade containing Lambeosaurus lambei and Saurolophus osborni , provided it does not include Hadrosaurus foulkii ". This clade excludes basal hadrosaurids such as Hadrosaurus and Yamatosaurus but self-destructs if Hadrosaurus

1500-459: The formal literature in Evans and Reisz's 2007 redescription of Lambeosaurus magnicristatus . Lambeosaurini is defined as all taxa more closely related Lambeosaurus lambei than to Parasaurolophus walkeri , and Parasaurolophini as all those taxa closer to P. walkeri than to L. lambei . In recent years Tsintaosaurini and Aralosaurini have also emerged. The use of the term Hadrosaurinae

1550-437: The formation. A member need not be mappable at the same scale as a formation. Formations are the primary units used in the subdivision of a sequence and may vary in scale from tens of centimetres to kilometres. They should be distinct lithologically from other formations, although the boundaries do not need to be sharp. To be formally recognised, a formation must have sufficient extent to be useful in mapping an area. A group

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1600-567: The group between the hollow-crested subfamily Lambeosaurinae and the subfamily Saurolophinae , historically known as Hadrosaurinae. Both of these have been robustly supported in all recent literature. Phylogenetic analysis has increased the resolution of hadrosaurid relationships considerably, leading to the widespread usage of tribes (a taxonomic unit below subfamily) to describe the finer relationships within each group of hadrosaurids. Lambeosaurines have also been traditionally split into Parasaurolophini and Lambeosaurini . These terms entered

1650-415: The main lithostratigraphic ranks are bed, member, formation, group and supergroup. Formal names of lithostratigraphic units are assigned by geological surveys . Units of formation or higher rank are usually named for the unit's type location , and the formal name usually also states the unit's rank or lithology. A lithostratigraphic unit may have a change in rank over a some distance; a group may thin to

1700-621: The north, east, and west . The sediments of Coon Creek were deposited near the end of the Cretaceous Period , around 71 million years ago. At that time western Tennessee, eastern Arkansas , western Kentucky , and southeast Missouri were submerged beneath the Mississippi Embayment , an extension of the Gulf of Mexico . Coon Creek was formed in shallow coastal water probably less than 100 feet deep . A couple of miles to

1750-433: The now scattered fossils in 1858, and these specimens as well were given to Leidy. They were described in the same year as Hadrosaurus foulkii , giving a slightly better picture of the form of a hadrosaur. Leidy provided additional description in a 1865 paper. Among his 1858 work Leidy briefly suggested that the animal was likely amphibious in nature; this school of thought about hadrosaurs would come to be dominant for over

1800-429: The purpose of the paddle-like hand Osborn had described, as well as their long and somewhat paddle-like tails. Thus he agreed with the idea that hadrosaurs would have taken refuge from predators in water. Numerous important studies would follow this; Ostrom's student Peter Dodson published a paper about lambeosaur skull anatomy that made enormous changes to hadrosaur taxonomy in 1975, and Michael K. Brett-Surman conducted

1850-654: The remains of indeterminate hadrosaur remains, as complete fossil skeletons of dinosaurs are a rarity in Appalachia . Sometimes the dried carcasses of dinosaurs were washed out to sea by rivers. Dinosaur bones and teeth have been found in marine deposits in Mississippi. It is possible that dinosaur bones will turn up at Coon Creek someday. The remains of at least two mosasaurs have been found. They were not dinosaurs but large aquatic lizards that could reach lengths of up to 45 feet. They were carnivorous and would have been

1900-409: The studies published therein. The first chapter of the volume was a study by David B. Weishampel about the rate of ornithopod research over history, and the interest in different aspects of it over that history, using the 2004 volume The Dinosauria as the source of data on the amount of works published in each decade. Various periods of high and low activity were found, but the twenty-first century

1950-539: The teeth of hadrosaurids are stacked into complex structures known as dental batteries , which acted as effective grinding surfaces. Hadrosauridae is divided into two principal subfamilies: the lambeosaurines ( Lambeosaurinae ), which had hollow cranial crests or tubes; and the saurolophines ( Saurolophinae ), identified as hadrosaurines (Hadrosaurinae) in most pre-2010 works, which lacked hollow cranial crests (solid crests were present in some forms). Saurolophines tended to be bulkier than lambeosaurines. Lambeosaurines included

2000-399: The top of the food chain in the Coon Creek area. Most organisms are not preserved as fossils. Unless covered quickly after death, their bodies are consumed by other animals and plants or destroyed by weather. Even the bones and shells of animals that were quickly buried after death may be later dissolved by groundwater. The clay in the sediment at Coon Creek sealed off the fragile fossils from

2050-541: The uplift was carried away. When the continent moved west past the hotspot, the cooled land minus the eroded 2 kilometers created a deep trough. When sea level rose nearly 500 feet, the trench was filled with seawater. The Mississippi Embayment stretched West from the Tennessee Valley to the area of Little Rock, Arkansas. It may have been 1,000 feet deep where Memphis is now. The embayment gradually filled with sand, clay, and gravel brought in by rivers on uplands to

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2100-492: The very first dinosaur fossils recognized from North America . These specimens were obtained by Joseph Leidy , who described and named them in 1856; two of the several species named were Trachodon mirabilis of the Judith River Formation and Thespesius occidentalis of the " Great Lignite Formation ". The former was based on a collection of teeth whilst the latter on two caudal centra and

2150-420: The warm, shallow sea, eating, reproducing, and being eaten Sohl 1960 Sohl 1964 . Giant reptilian mosasaurs, highly ornamented cephalopods, and other less familiar sea creatures lived in the water. Their shells, bones, carapaces, teeth, and other hard parts were constantly being buried in the sandy mud of the seafloor. The lack of distinct layering indicates that clams, shrimps, and other burrowing organisms mixed

2200-424: The waters with sharks and fierce fanged-tooth fishes. The climate was warmer than today. Coon Creek was semi-tropical, like present-day southern Florida . Heavy waves from severe tropical storms constantly churned up shallower parts of the seafloor. Many rivers fed into the sea bringing leaves and driftwood from the land. These served as the base of the food chain. Bacteria and other microscopic scavengers ate

2250-442: Was almost completely preserved in the form of impressions. The skin around its hands, thought to represent webbing, was seen as further bolstering the idea that hadrosaurs were very aquatic animals. Cope had planned to write a monograph about the group Ornithopoda , but never made much progress towards it before his death. This unrealized endeavor would come to be the inspiration for Richard Swann Lull and Nelda Wright to work on

2300-429: Was backed using evidence of the environment and climate they lived in, co-existing flora and fauna, physical anatomy, and preserved stomach contents from mummies. Based on evaluation of all this data, Ostrom found the idea that hadrosaurs were adapted for aquatic life incredibly lacking, and instead proposed they were capable terrestrial animals that browsed on plants such as conifers . He remained uncertain, however, as to

2350-505: Was formed when the North American continent, driven by tectonic forces passed over a magma hotspot. The region had been weakened by rifts and faults during the breakup of Rodinia nearly 1 billion years ago. The pressure of the hotspot caused the rifted region to rise nearly 2 km from western Kentucky to northwestern Louisiana in an arch 300 km. wide. Millions of years of sediment were subjected to erosion and nearly all of

2400-440: Was found to overwhelmingly be the most prolific time, with over two-hundred papers published. The advent of the internet was cited as a likely catalyst for this boom. Hadrosaur research experienced high levels of diversity within the decade, with previously uncommon subjects such as growth, phylogeny, and biogeography experiencing more attention, though the functional morphology of hadrosaurids was found to have declined in study since

2450-419: Was questioned in a comprehensive study of hadrosaurid relationships by Albert Prieto-Márquez in 2010. Prieto-Márquez noted that, though the name Hadrosaurinae had been used for the clade of mostly crestless hadrosaurids by nearly all previous studies, its type species, Hadrosaurus foulkii , has almost always been excluded from the clade that bears its name, in violation of the rules for naming animals set out by

2500-412: Was re-evaluated and many of them redescribed. They agreed with prior authors on the semi-aquatic nature of hadrosaurs, but re-evaluated Cope's idea of weak jaws and found quite the opposite. The teeth were rooted in strong batteries and would be continuously replaced to prevent them getting worn down. Such a system seemed incredibly overbuilt for the job of eating soft Mesozoic plants, and this fact confused

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