Old Earth Ministries Online Earth History Curriculum
Presented by Old Earth Ministries (We Believe in an Old Earth...and God!)
This curriculum is presented free of charge for use by homeschooling families.
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Chapter 10 - The Jurassic Period
Lesson 51: Plesiosaurs
plesiosaur was a type of carnivorous aquatic (mostly marine) reptile. After
their discovery, plesiosaurs were somewhat fancifully said to have resembled
"a snake threaded through the shell of a turtle",
although they had no shell. The common name "plesiosaur" is applied both to
the "true" plesiosaurs (Superfamily
Plesiosauroidea), which include both
and short-necked (polycotylid)
forms, and to the larger taxonomic rank of
Plesiosauria, which includes the
pliosaurs. The pliosaurs were the
short-necked, large-headed plesiosaurians that were the
apex predators for much of the
Mesozoic. There were many species of
plesiosaurs, while most of them were not as large as
Chapter 10 - The Jurassic Period
Dolichorhynchops, a short-necked, long-jawed plesiosaur, National Museum of Natural History, Washington D.C. (Picture Source)
Plesiosaurs appeared at the start of the Jurassic Period and thrived until the K-T extinction, at the end of the Cretaceous Period. While they were Mesozoic reptiles that lived at the same time as dinosaurs, they were not dinosaurs.
The first plesiosaur skeletons were found in England by Mary Anning, in the early 1800s, and were amongst the first fossil vertebrates to be described by science. Many have been found, some of them virtually complete, and new discoveries are made frequently. One of the finest specimens was found in 2002 on the coast of Somerset (England) by someone fishing from the shore. This specimen, called the Collard specimen after its finder, was on display in Taunton Museum in 2007. Another, less complete skeleton was also found in 2002, in the cliffs at Filey, Yorkshire, England, by an amateur paleontologist. The preserved skeleton is displayed at Rotunda Museum in Scarborough.
Many museums have plesiosaur specimens. Notable among them is the collection of plesiosaurs in the Natural History Museum, London, which are on display in the marine reptiles gallery. Several historically important specimens can be found there, including the partial skeleton from Nottinghamshire reported by Stukely in 1719 which is the earliest written record of any marine reptile. Other specimens include those purchased from Thomas Hawkins in the early 19th century.
Specimens are on display in museums in the UK, including New Walk Museum, Leicester, The Yorkshire Museum, The Sedgwick Museum in Cambridge, Manchester Museum, Warwick Museum, Bristol Museum and the Dorset Museum. A specimen was put on display in Lincoln Museum (now The Collection) in 2005. Peterborough Museum holds an excellent collection of plesiosaur material from the Oxford Clay brick pits in the area. The most complete known specimen of the long-necked plesiosaur Cryptoclidus, excavated in the 1980s can be seen there.
Plesiosaurs had a broad body and a short tail. They retained their ancestral two pairs of
pliosaurian cousins, plesiosaurs (with the exception of the Polycotylidae)
were probably slow swimmers. It is likely that they cruised slowly below the
surface of the water, using their long flexible neck to move their head into
position to snap up unwary fish or cephalopods. Their four-flippered
swimming adaptation may have given them exceptional maneuverability, so that
they could swiftly rotate their bodies as an aid to catching prey.
Source Page: Plesiosaur