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Ichthyosaur Temnodontosaurus E42 Lyme Regis Museum Ichthyosaur “E42”

by Phil Davidson and Ben Brooks

 

An Ichthyosaur, Temnodontosaurus Platyodon was found east of Lyme Regis by Mr Henry Ellis probably over 100 years ago and was donated to Lyme Regis Museum by Mrs Luttill in 1927. The composite specimen was prepared by David Costin in 1985 and a cast made which hangs in the museum's Geology Gallery. The cast can be seen in the Gigapan photograph of the gallery.

In 2012/13, geologists Phil Davidson and Ben Brooks carried out a detailed examination of the foss which is stored in the museum's cellar in boxes labelled E42 and has been nicknamed "The Beast in the Cellar" (see our article in Fossil Finds on the Beach). This article is derived from the notes and photographs taken during the geological examination.

 

Fig. 1.: Composite photograph of Lyme Regis Museum Ichthyosaur “E42”

Fig. 1.: Composite photograph of Lyme Regis Museum Ichthyosaur “E42”

Click the above picture to explore in high resolution (6Mb file)

Below are transcribed the observations made by Phil Davidson and Ben Brooks on the current state of the Ichthyosaur stored in the basement of Lyme Regis Museum. The Ichthyosaur is assumed to be of the Genus Temnodontosaurus due to its size. The specimen measures approximately 4.2 metres in length, and is broken into 18 blocks (though the rear paddle (block q on fig. 1.) is broken down further into three pieces, one of which may not be the original).

 

 

Block number in   photograph above & size

 

Photograph of block

 

Description of block

Block a

15 x 21cm

Block a
  • Segment of Rostrum in Beef.
  • Heavily pyritised, decay evident.
  • Teeth visible in cross section.
  • Burrow traces visible on some bone surfaces.

Block b

33 x 45cm

Block b
  • Jaw section.
  • Pyrite decay on anterior end of reverse.
  • 1 visible repair.
  • Burrow traces visible between jaws and on the sides of the block.
  • 2 oysters/xenomorphs at posterior on reverse.

Block c

36 x 57cm

Block c
  • Converging mandible fragments (lower jaw).
  • heavily pyrite decayed.
  • 3 large resin repairs.
  • 1 large ammonite impact on reverse (tentative identification: Asteroceras Stellare)
  • Bivalve shells and fragments on reverse.
  • Burrow traces on side of block.

Block d

26 x 64cm

Block d

Block d cross section

  • Rear Section of Skull
  • Vertebrae – 2 Centra, 1 partial neural spine/hyoid?, 1 Surangular?, 2 partial hyoid? 2 other skull bones (poss. atlas/axis).
  • Calcite veins common, almost septarian. Repairs visible on reverse.
  • Possible bones on reverse (highly eroded/damaged).
  • Many cross-sectioned bones visible throughout.

Block e

37 x 72cm

Block e
  • Rear Section of Skull
  • Vertebrae – 2 Centra, 1 partial neural spine/hyoid?, 1 Surangular?, 2 partial hyoid? 2 other skull bones (poss. atlas/axis).
  • Calcite veins common, almost septarian. Repairs visible on reverse.
  • Possible bones on reverse (highly eroded/damaged).

Block f

40 x 74cm

Block f
  • Trunk Section
  • Vertebrae – 4 complete, 2 partial.
  • Neural spines – 4 complete, 1 partial
  • 10 partial ribs, 2 partial ammonites.
  • Calcite veins, apparently stable pyrite patches.
  • 2 Previous Repairs

Block g

38 x 90cm

Block g
  • Trunk Section
  • Vertebrae – 2 centra, 2 partial
  • 7 – 10 partial ribs
  • 2 neural spines?
  • Fish scales visible around vertebrae (also poss. soft part preservation?)
  • Patchy pyrite, at worst around vertebrae.

Block h

46 x 89cm

Block h
  • Trunk Section
  • Vertebrae – 6 whole, 1 partial.
  • 13 partial ribs, 6 neural spines.
  • Some pyrite contents.
  • 1 Belemnite above anterior centrum.

Block i

29 x 46cm

Block i
  • Section of rib cage
  • 10 partial ribs in a cross hatched pattern.
  • 1 area of possible fish remains (ray or scales).
  • Pyrite throughout, appears stable
  • Clear burrow traces on side.

Block j

56 x 73cm

Block j
  • Trunk Section
  • Vertebrae – 7 centra, 1 partial.
  • 21 partial ribs, 6 partial neural spines
  • Some possible soft parts.
  • Some squashed ammonites (probably body chambers only), gypsum and pyrite between 2 centra.
  • Some calcite veining.

Block k

28 x 63cm

Block k
  • Section of rib cage
  • 12 partial ribs.
  • Possible soft parts.
  • 1 possible fish rib.
  • Burrow traces visible
  • 4 repairs - 1 resin, 3 grit & glue

Block l

31 x 35cm

Block l
  • Section of vertebral column
  • Vertebrae – 5 centra, 1 partial rib, more cross sectioned on side.
  • 2 neural arches. Other misc. Bones
  • Burrow traces visible. Pyrite decay on reverse.
  • Large crack along dorsal side.

Block m

19 x 32cm

Block m
  • Section of vertebral column
  • Vertebrae – 5 complete centra,
  • 1 poss. rib on reverse.
  • Patches of Pyrite, some decay.
  • Burrows and a sedimentation interface on sides of block

Block n

18 x 43cm

Block n
  • Section of vertebral column
  • Vertebrae – 6 centra, clay from casting process.
  • Some pyrite. 3 resin repairs.

Block o

35 x 69cm

Block o
  • Near complete front paddle inc. Humerus head/Radius/Ulna and Phalanges.
  • 36 bones total, 33 complete.
  • Distal phalanges missing, small amount of pyrite between Radius, Ulna and Humerus.
  • Many phalanges appear septarian.
  • Notching on Radius and Radiale.
  • Possible burrow marks.
  • Repairs visible on both sides.
  • Some cross sectioned bones at proximal end.

Block p

22 x 29cm

Block p
  • Partial Paddle
  • 1 partial paddle, 19 bones total, 15 complete.
  • 1 long bone on reverse beneath dislocated phalanges.
  • Some burrow traces.
  • Bone surface noticeably poorer than other paddle bones.

Block q

29 x 57cm

Block q
  • Near complete paddle.
  • 32 bones total, 30 complete.
  • Broken along prior repair, small fragment may not be original.

Block r

28 x 60cm

Block r
  • Partial paddle.
  • Including a single bone of the pelvic girdle (Ischium or Pubis).
  • 2 previous repairs.
  • 4+ cracks in need of attention.
  • Some pyrite between phalanges, apparently stable except on edges of block.

Areas with visible quantities of pyrite disease/decay products

Pyrite Decay

 

Areas with possible soft part preservation/gut contents

Possible Soft Parts

 

 

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