Lubow 1 Brandon Lubow Dr. Parker IFS2087 16 November 2015 Mosasaurus: The Reptile that Ruled the Sea Abstract Throughout the history of Earth, few apex predators have existed like Mosasaurus. This terrifying creature ruled the depths in the Late Cretaceous, growing as large as 60 feet in length, and weighing as much as 15 tons. Commonly mistaken as a dinosaur, Mosasaurus is in fact a reptile. Mosasaurus also needed oxygen to survive requiring that it rise to the surface periodically to breathe. This enormous carnivore is known for eating anything in its sight, including other Mosasaurs. It is often related to snakes and monitor lizards due to the characteristics it shares with the two. Mosasaurus went extinct at the end of the Cretaceous.
Lubow 2 Introduction The biggest, baddest dinosaurs are always what draws in a crowd and everyone knows it. But what about a big, bad reptile? When you take a look at the movie Jurassic World, the Mosasaurus feeding show, held every two hours, sure does fill up the seats. Of course not many people know that Mosasaurus is in fact a reptile, rather than a dinosaur. The enormous sea-bound creature ruled the depths in the Maastrichtian of the Cretaceous (Late Cretaceous), about 70-65 million years ago (Strauss, 2015) before becoming extinct approximately 66 million years ago during the KT Mass Extinction. The first Mosasaurus fossil (Mosasaurus hoffmannii) was found in the Netherlands in 1764, consisting of just a fragmentary skull. Dutch scientist, Martinus van Marum, first mistook the fossil to be a fish. Another incomplete skull was found near the original discovery by Johann Leonard Hoffmann, on property owned by Theodorus Joannes Godding in the 1770s, shown in Figure 4. Hoffmann brought much more interest to this new creature through his discovery of other remains. In 1822, William Daniel Conybeare named the organism Mosasaurus. Mosasaurus fossils have been found on every continent on Earth indicating they were a very widespread and plentiful species (Mancini, 2015). It was not until 1854 that Mosasaurus was suggested to be an aquatic creature by Hermann Schlegel. (Mosasaurus, 2011) Mosasaurus could grow to almost 60 feet long (18 m) weighing around 15 tons! The immense size of Mosasaurus relative to that of other Mosasaurs is shown in Figure 1. Most Mosasaurus were in the 20-30 foot range though. (About Mosasaurus, 2015) Mosasaurs had body shapes similar to modern-day monitor lizards but were more elongated and adapted for swimming. Their appendages were also quite short and primarily used for turning while their flattened tails provided the power needed for movement. (Mosasaur, 2014) Long, narrow, cone-
Lubow 3 shaped heads similar to that of a barracuda helped plow through the water just as a plane does through the air. (Mosasaur, 2014) The Mosasaur, unlike most sea creatures, needed oxygen to survive. They were required to occasionally rise to the surface of the water to breathe giving us clue that they probably didn t dive to extreme depths. (ibid.) Mosasaurus falls under the Animalia kingdom, Chordata phylum, Reptilia class, Squamata order, Mosasauridae family, and Mosasaurinae subfamily. (Mosasaur Facts and Info, 2015) Discussion The root of the name Mosasaurus, Mosasaur, was derived from the location in which the Mosasaurus was first discovered. The name means Lizard of the Meuse River with Mosa representing the Muese River in Holland, the location of the discovery, and Saur being the greek word for lizard. Given that Mosasaurus is in fact a reptile rather than a dinosaur, the name is quite fitting. (Mosasaur Facts and Info, 2015) Although the first Mosasaurus was discovered in 1764, the species was not assigned a generic name until 1822 by William Daniel Conybeare. Seven years later, in 1829, Mosasaurus was given a species name, Mosasaurus hoffmannii, by Gideon Mantell. (Mosasaurus, 2011; Everhart, 2010) The first Mosasaurus fossil consisted of simply a fragmentary skull which led to many incorrect suggestions as to what creature it belonged to. The first study by Martinus van Marum led to the conclusion that the skull belonged to a fish because there was no knowledge of any giant marine reptiles at this time. Johann Leonard Hoffmann found another incomplete skull in the 1770s, shown in figure 4. Hoffmann was taken to court by Theodorus Joannes Godding who claimed the fossil belonged to him because it was found on his land. Hoffmann was forced to give up the fossil but later discovered more remains belonging to Mosasaurus which led to an
Lubow 4 increased popularity in the creature. Hoffmann believed the fossil belonged to some sort of ancient crocodile. Even Petrus Camper, a Dutch professor, misidentified the fossils as that of an ancient sperm whale. The fossils were examined and studied by Barthélemy Faujas de Saint- Fond while in France and were again mistaken for those of an ancient crocodile. While looking over his father s (Petrus Camper) notes, Adriaan Gilles Camper found that he disagreed with both the suggestion that the fossils were that of an ancient crocodile or ancient sperm whale. Instead, Camper believed they belonged to a giant monitor lizard, which turned out to be quite an accurate conclusion due to the widespread belief that Mosasaurus actually evolved from monitor lizards. In 1808, Georges Cuvier confirmed Camper s claim by using comparative anatomy to identify unknown bones. (Mosasaurus, 2011; Everhart, 2010) The Mosasaurus ruled the oceans during the late Cretaceous, or Maastrichtian, about 70-65 million years ago. (Giant Mosasaur, 2003; Strauss 2015) Like I stated earlier, the Mosasaurus is believed to have evolved from land roaming reptiles eventually making their way to the seas and disappeared around the same time all of the dinosaurs went extinct. This event is known as the KT Mass Extinction due to its occurrence falling between the Cretaceous (K) and Tertiary (T) periods. More than three-fourths of all living species on Earth went extinct because of this event. (The K-T Mass Extinction, 2008) Mosasaurus were one of the largest creatures roaming around beneath the surface. Due to their immense size, reaching up to 18 meters, the only predators they had to worry about were other Mosasaurs. To get a better idea of how large Mosasaurus could really grow to be, take a look at both figures 1 and 2. Mosasaurus reached full size at around the same time an average T-rex would, 20 years old. (Everhart, 2009) Although it is tough to determine mass or weight of a Mosasaurus from solely fossil evidence, weight estimates fall around 15 tons with a maximum
Lubow 5 of 20 tons! (Strauss, 2015; Giant Mosasaur, 2003) With a creature of that size and weight, it must ve generated an immense amount of power with its tail considering it was the only part of the body used for propulsion. Also given the fact that Mosasaurus are believed to have swum like most modern snakes, you have to imagine that they were probably quite agile in the water. In 1854 it was suggested, by Hermann Schlegel, that Mosasaurus appendages were in fact flippers and not feet (Mosasaurus, 2011). This was the first hint that Mosasaurs were not land roamers, but instead bound to the water. It is believed that the Mosasaurus evolved from land reptiles whose arms and legs developed into hydropedal limbs. Given that Mosasaurs are reptiles, they were required to rise to the surface of the water periodically to breathe. With this information in mind, it is likely that Mosasaurs didn t dive to extreme depths. (About Mosasaurus, 2015) Mosasaurus were carnivores, eating things like fish, ammonites, sharks, and even other Mosasaurs (Everhart, 2011; Pappas 2013). A fossil found in Alberta, Canada helped us determine this. Shortly after eating a meal, this Mosasaurus actually became a meal itself. The upper half of it still remained though, even after being scavenged by at least three sharks, and was fossilized with what was in its stomach as well. It was discovered that the Mosasaurus had eaten a type of fish called a grinner and its bones were fossilized as well, helping us determine that Mosasaurus was a carnivore and sometimes cut its food into pieces with its teeth. (Switek, 2014) It is unclear whether the remains of Mosasaurs found in Mosasaurus stomachs came off of living organisms or simply corpses that it may have stumbled upon. Fossil evidence has shown us that Mosasaurus ate all parts of its prey, including the bones. There have been some instances where shark teeth have been found embedded in Mosasaurus bone, indicating that
Lubow 6 some sharks may have eaten Mosasaurus but it is likely they only went after the young ones or the ones who had already died. (About Mosasaurus, 2015) Knowing just how large Mosasaurus could grow to be, one might begin to wonder how much food they really ate. We know that Mosasaurus were carnivores, but that leaves us with the question of how they were able to catch prey given their enormous mass. This sea bound reptile was actually quite intelligent: When potential prey would get near the Mosasaurus it would act as if it had no interest in eating. Then, when the prey got close enough, the Mosasaurus would use the thrust of its extremely powerful tail to outrun its prey with a short burst of speed. (Everhart, 2009) This was determined through the discovery of the Ectenosaurus clidastoides, a Mosasaurus fossil, which contained extremely well preserved muscle fiber bundles. Johan Lindgren used this to discover that it generated the power needed for movement with solely its tail. This type of swimming is similar to that of sharks and crocodiles. (Lindgren, Everhart, & Caldwell, 2011) Not only this but the Mosasaurus had some special adaptations that served as advantages when hunting prey. One of these was the double-hinged jaw, or the ability to separate or unhinge its jaw, similar to snakes today, allowing it to swallow fish and other creatures larger than its own head. Of course its 40-50 sharp, cone-shaped teeth aided in the holding or restraint of prey (Matthew, 2015). Mosasaurus, similar to T-Rex s, ate all parts of prey including the bones rather than picking around the bones of the corpse. Another helpful tool was an adaptation in the lower jaw that allowed them to flex in the middle, enabling Mosasaurus to swallow large fish and other food. (Everhart, 2009) This deadly reptile actually had a second set of teeth in its upper palate, shown in figure 3, to ensure no prey would be able to escape its mouth (Mosasaurus, 2015).
Lubow 7 Similar to modern day whales, the Mosasaurus was required to rise to the surface to breathe. While some whales can hold their breath for as long as two hours, it is unclear exactly how long a Mosasaurus could remain submerged without coming up for air (How Come Whales, 2015). Another thing that made Mosasaurus different from most organisms during this time is the fact that they gave live birth, while others laid eggs. (About Mosasaurus, 2015) This characteristic is even more unusual given that Mosasaurus was a reptile. The fossil that gave us this information is a Plioplatecarpus specimen. This mother Mosasaur was found in South Dakota with remains of her unborn young around her, instilling us with the knowledge that Mosasaurs give live birth rather than lay eggs. (Mancini, 2015) Mosasaurus also possessed diamond shaped scales similar to that of its reptilian counterpart, snakes. Keeled scales protected the upper part of the Mosasaur, while smooth scales did the same for the lower parts. A recent discovery even determined that Mosasaurus were counter shaded and had a black back and white underside. (ibid.) When it comes to phylogeny the Mosasaurus falls under the Animalia kingdom, the Chordata phylum, the Reptilia class, Squamata order, Mosasauridae family, and Mosasaurinae subfamily (Mosasaur Facts and Info, 2014). Edward Drinker Cope suggested Mosasaurs and snakes shared common ancestors based on their flanged teeth, reduced limbs, double-hinged jaw, and likely style of movement. (About Mosasaurus, 2015) The fossil, Dallasaurus turneri, may serve as the missing link between Mosasaurs and their relatives. Dallasaurus shared characteristics with both Mosasaurs and Aigialosaurids, a reptilian sea creature that lived before the Mosasaurus. (ibid.) A controversial issue in the taxonomy of Mosasaurus is the uncertainty of whether they should be considered monophyletic or polyphyletic. In other words, do the Mosasaurs all have a single ancestral background or did they evolve from multiple organisms?
Lubow 8 (ibid.) Another question arises in their placement under the Squamata order, being, what is their relationship to snakes? Some scientist even place Mosasaurs under the Scleroglossa order, a sister taxa to Squamata. (About Mosasaurus, 2015) The Mosasaurus went extinct at the end of the Cretaceous as a result of the KT Extinction. This period also marked the end of the Maastrichtian, the Mesozoic, and the presence of dinosaurs on Earth. It is believed that this was caused by an asteroid strike in the northern part of the Yucatan Peninsula. New research suggests there may have been more than one asteroid strike, along with volcanic activity. These environmental occurrences led to a domino type effect eventually causing the extinction of 75% of the Earth s inhabitants. (The Mosasaurs, 2015) As far as portrayals of the Mosasaurus goes, they aren t completely accurate. According to Hans-Dieter Sues, National Museum of Natural History Curator of Vertebrate Paleontology, The Mosasaur in the pool is twice the size as the largest actually known species, Sues said. Plus, it should have a forked tongue, in response to the Jurassic World portrayal of Mosasaurus (Ohlheiser, 2014). Conclusion First and foremost, Mosasaurus were reptiles and not dinosaurs. The Mosasaurus inhabited the seas during the Late Cretaceous. They were also bound to the ocean with no way of being able to move around on land. Mosasaurus also require oxygen to survive and must have risen to the surface periodically to breathe. Mosasaurus were carnivores who occasionally turned to cannibalism. These creatures reached extreme sizes of almost 60 feet in length. They are considered to be closely related to snakes and monitor lizards because of their double hinged jaws and movement techniques. The Mosasaurus was one of the few reptiles to give live birth.
Lubow 9 They went extinct at the same time as all dinosaurs due to the KT Extinction. There hasn t been a creature this terrifying since. After all, they didn't call it the T-Rex of the ocean for nothing.
Lubow 10 Figures 1. (1) Halisaurus (2) Pannoniasaurus (3) Plioplatecarpus (4) Carinodens (5) Globidens (6) Platecarpus (7) Plesioplatecarpus (8) Plesiotylosaurus (9) Yaguarasaurus (10)Clidastes (11)Hainosaurs (12)Liodon (13)Prognathodon (14)Plotosaurus (15)Tylosaurus (16)Mosausaurus (17)Taniwhasaurus (18)Moanasaurus Figure 1 is a diagram that shows the relative size of different types of Mosasaurs. The different labels indicate the type of Mosasaur each picture corresponds with. This photo was retrieved from www.prehistoric-wildlife.com (The Mosasaurs, 2015)
Lubow 11 2. Figure 2 shows the comparative size of a fully grown Mosasaurus (about 18 m) to that of a fully grown human (1.8 m). The sizes are equivalent to approximately 59 feet and 6 feet respectively. This photo was retrieved from www.prehistoric-wildlife.com (Mosasaurus, 2011) 3. Figure 3 is a photo from the movie Jurassic World. If you look close enough into the Mosasaurus mouth you can see the second set of teeth in its upper palate used to ensure no prey can escape from its mouth. Although the portrayal of the mouth is accurate, the size of the Mosasaurus body is much larger than it would be in reality. This picture was retrieved from https://www.reddit.com/r/wallpapers/comments/35eoc2/mosasaur_from_jurassic_world_ 2560x1600/
Lubow 12 4. Figure 4 is a photo of the Mosasaurus hoffmannii fragmented skull found by Theodorus Joannes Godding in the 1770s. This photo was retrieved from https://en.wikipedia.org/wiki/mosasaur
Lubow 13 Cited References BBC. "Giant Mosasaur." BBC News. BBC, 2003. Web. 13 Nov. 2015. ClassZone. "The K-T Mass Extinction." ClassZone. McDougal Littell, 2008. Web. 18 Nov. 2015. Everhart, Mike. "A Day in the Life of a Mosasaur." Oceans of Kansas. 2001-2009 by Mike Eberhart, 10 Aug. 2009. Web. 13 Nov. 2015. Everhart, Mike. "Just About Mosasaurs." Oceans of Kansas. 1996-2011 by Mike Everhart, 4 Mar. 2011. Web. 13 Nov. 2015. Everhart, Mike. "Mosasaurus Hoffmanni - The First Discovery of a Mosasaur?" Oceans of Kansas. 1999-2010 by Mike Everhart, 14 May 2010. Web. 13 Nov. 2015. Fossil Era. "About Mosasaurus & Mosasaurs." FossilEra. 2015 FossilEra, 2015. Web. 13 Nov. 2015. Fossil Guy. "Mosasaur Facts and Information - The Great Marine Reptiles of the Cretaceous." - Fossilguy.com. 2015: FOSSILGUY.COM, 2014. Web. 13 Nov. 2015. Jurassic World. "Mosasaurus." Jurassic World. 2015 Universal Studios & Ambling Entertainment, Inc., 2011. Web. 13 Nov. 2015. Lindgren Johan, Everhart Michael J., Caldwel Michael W. (2011) Three-Dimensionally Preserved Integument Reveals Hydrodynamic Adaptations in the Extinct Marine Lizard Ectenosaurus (Reptilia, Mosasauridae). PLoS ONE, 2011; 6 (11): e27343 DOI: 10.1371/journal.pone.0027343 Mancini, Mark. "6 Amazing Mosasaur Facts to Prepare You For 'Jurassic World'" Mental Floss. 2015 Mental Floss, Inc., 9 June 2015. Web. 13 Nov. 2015. Matthew, Lee. "Megalodon vs Mosasaurus: Who Would Win?" FossilEra. 2015 FossilEra, 6 May 2015. Web. 13 Nov. 2015. Montanari, Shaena. "A Paleontologist Reviews 'Jurassic World'" Forbes. Forbes Magazine, 12 June 2015. Web. 13 Nov. 2015. New World Encyclopedia. "Mosasaur." New World Encyclopedia. MediaWiki, 24 Nov. 2014. Web. 13 Nov. 2015. Ohlheiser, Abby. "A Smithsonian Paleontologist Fact-checked the Jurassic World Trailer. His Take? Meh.." Washington Post. The Washington Post, 29 Nov. 2014. Web. 13 Nov. 2015.
Lubow 14 Pappas, Stephanie. "Mosasaur Cannibalism? Fossilized 'Sea Monster' Found In Angola With Three Others In Its Belly." Southern Methodist University. Southern Methodist University, 5 Nov. 2013. Web. 18 Nov. 2015. Prehistoric Wildlife. "Mosasaurus." Prehistoric Wildlife. Www.prehistoric-wildlife.com 2011-2015, 2014. Web. 13 Nov. 2015. Prehistoric Wildlife. "The Mosasaurs. Prehistoric Wildlife. Www.prehistoric-wildlife.com 2011-2015, 2015. Web. 13 Nov. 2015. State Historical Society of North Dakota. "Mosasaur Fun Facts." (n.d.): n. pag. State Historical Society of North Dakota. 2015 State Historical Society of North Dakota. Web. 13 Nov. 2015. Strauss, Bob. Mosasaurus - The Deadliest Marine Reptiles About.com Education. 2015 About.com, 2015. Web. 13 Nov. 2015. Switek, Brian. "A Mosasaur s Last Meal." National Geographic. 1996-2015 National Geographic Society, 15 Sept. 2014. Web. 13 Nov. 2015. UCSB. "How Come Whales Can Hold Their Breath Longer than Most Mammals?" UCSB Science Line. The Regents of the University of California, 2015. Web. 18 Nov. 2015.