Few Earth Science departments are as fortunate as we are in Glasgow
in being closely linked to the collections and curatorial expertise of
a major museum. The Hunterian Museum was founded and made available to
the public in 1807 and thus is Glasgow's oldest public museum. It takes
its name from Dr
William Hunter who was Queen Charlotte's (wife of George III) gynaecologist
and a major collector of works of art, manuscripts, coins and medical,
archaeological, ethnographical and natural history materials. His vast
and priceless collection was bequeathed to Glasgow University in 1783.
Most of the million or so geological specimens have been acquired since
that date either by individual donation or through the acquisition of important
research collections, some from the academic and museum staff and research
students. Willaim Hunter's brother, also a medical man, founded another
Hunterian Museum at what is now the Royal College of Surgeons in London.
The museum is undergoing continuing major refurbishment and there are many new exhibits and important specimens worth seeing. The curatorial staff in geology will always endeavour to show you material from the collections (by arrangement) and will help with identification of material you have collected yourself. These facilities are at your disposal: please make full use of them.
The aim of the practical is to introduce you to the Museum (if you haven't visited it before) and to enable you to have 'hands-on' experience especially of some aspects of vertebrate palaeontology. Many of the topics continue themes from the lectures and the invertebrate fossil labs. The practical should at least provide you with insights into some important facets of the history of life on Earth.
Some of the vertebrate fossils you will be examining are preserved
as complete skeletons (in some cases articulated); others as isolated bones.
Q.1. Which of these types of preservation do you think is most common
in the geological record? What environmental conditions are required for
the preservation of complete skeletons?
Bone is composed of calcium phosphate and has a porous structure. It is therefore
relatively light.
Q.2. Examine the sub-fossil giant deer jaw
from the late Pleistocene of Ireland and the Pleistocene (about 2 million year
old 'Ma') mammoth tusk. Compare these
with the Mid Jurassic (about 160 Ma) pliosaur
bones and teeth in the lab. and on display (Exhibit 8D). Explain their different
densities.
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Pyrite is a common diagenetic mineral growing in the pores of fossil
bone or even replacing the bone material. Under damp conditions in air
it reacts with water to produce sulphuric acid which reacts with bone and
other substances to produce calcium sulphate (gypsum). This is termed 'pyrite
rot'.Q.1. Examine the effects of 'pyrite rot' seen in the limb bone of
the Jurassic ichthyosaur Ophthalmosaurus and in the plesiosaur ribs
(compare with unaffected ribs). Describe the physical effects of 'pyrite
rot'.
Such deterioration of fossil vertebrate material is a common problem
and conservation measures have to be undertaken to prevent the complete
loss of the specimens
Q.2. Examine and describe the specimens of plesiosaur ribs and the
repaired limb bone of another Jurassic plesiosaur, Cryptoclidus.
The latter literally exploded in a packing case when housed in a rather
damp store.
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Q.3. What measures should a museum take to prevent the decay of such valuable fossil material?
Complete but disarticulated vertebrate skeletons need to be carefully
repaired and reassembled in order to understand the morphology of the animal.
The Hunterian Museum has very many scales and bones of a very large (over
2m) holostean fish, Lepidotes latifrons, from the Middle Jurassic
Lower Oxford Clay near Peterborough.
These are being painstakingly reassembled and a partial
reconstruction is in case 8B. This is the largest known specimen of
this species; the type specimen of this species in the Natural History
Museum in London is only about half this size.
Q.1. In the lab., examine the replica of part of the reconstructed
head. Compare the weight of the latter with that of one of the genuine
skull roof bones. Marvel at the patience and skill required for such a
reconstruction.
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Q.2. Why do you think plastic replicas are being made of reassembled
sections of this fossil?
Q.3. Compare this material with the Lower Jurassic specimen of L. elvensis
on display in the museum (wall case 4E) Note and explain the differences.
Reconstructed skeletons make very effective displays.
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Q.4. Examine the museum display (exhibit 8A) of the plesiosaur Cryptoclidus
eurymerus and make notes on the mode of life of this Jurassic marine
reptile. How did it swim? (click here to see the
skeleton on display)
How did it reproduce (n.b. most reptiles lay eggs)?
Q.5. Examine the reconstructed bones of C. eurymerus in the lab. What part of
its skeleton do they belong to?
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Trace fossils are a record of the activities of animals preserved
in or on sediments such as tracks, trails, burrows and borings. Vertebrate
footprints are trace fossils which can provide a lot of information about
the animal which made them.
Q.1. Examine the track of the Cretaceous (about 140Ma) dinosaur (exhibit
6E) both from close-up and from a distance. Note the impressions of the
three digits which have the inner toe shorter than the outer - a characteristic
of Iguanodon and its relatives. Interpret the gait (walking) pattern of
Iguanodon from its track.
Q.2. Examine the only known Scottish dinosaur footprint (from the Middle Jurassic (about 180Ma) of Skye) (exhibit 6G).
Q.3. Examine the trackway made by the Carboniferous 'millipede' Arthropleura in exhibit 6C. A half-scale model of the animal together with a specimen and limb replica are on display (exhibit 6B). Note its size.
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Q.4. Small animals can leave tracks and trails too. Examine the exhibit showing some of these.
Similar morphologies can be evolved by unrelated animals adopting
similar modes of life (convergent evolution).
Q.1. Examine and sketch the skeletons of the marine reptiles Stenopterygius (an ichthyosaur) and Metriorhynchus (a marine crocodile) and the model of Mosasaurus (a marine lizard). Note and interpret the similarities in overall body plan. What other vertebrates show similar morphologies? Note the modern skull in the lab. What do you think it might belong to? See also the ichthyosaur on display - exhibit 7A and particularly the one showing carbonised soft tissue in exhibit 10A.
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Q.2. Note the replica of the long dentary (part of the lower jaw - below) of
another ichthyosaur, Opthalmosaurus
in the lab. How big do you think the whole animal was (compare with complete
skeletons mentioned in Q.1)?
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Exhibits 9A-D illustrate various aspects of the evolution and demise
of this important vertebrate group. Virtually all the specimens on display
can be used to illustrate the theme of 'form and function'.
Q.1. In exhibit 9C are specimens showing the dental attributes of two
major dinosaur groups and their dietary lifestyles.
(a) Note the serrated 'steak knife' style teeth of the carnivores.
What was their function?
(b) Note the batteries of cheek teeth attached to the maxilliary bone
in a large herbivore. How did they function? Bear in mind that mammals
chew by moving the jaw sideways. No reptile (including dinosaurs) possessed
this facility, the jaw having only up and down motion. How, therefore,
do you think chewing could be achieved?
(c) Note in both instances how worn out teeth were lost and replaced
continuously.
(d) In the sauropod skull replica (Diplodocus) in exhibit 9B, note
the peculiar frontal batteries of peg-like teeth. How do you think they
functioned?
Q.2. Examine the recently mounted femur replica of a Middle Jurassic sauropod from Skye. Compare it with that in the mounted leg of Diplodocus carnegiei.
Q.3. Examine the exhibit containing a carefully prepared slab of dinosaur
eggs from the Cretaceous of Mongolia. They are thought to belong to
a sauropod dinosaur. Superficially, they all look complete but you are
seeing their undersides, some of them having hatched from the concealed
upper side. 'CAT-Scan' imagery (available in the laboratory) shows that
at least one egg - the isolated one at the end of the block and possibly
also the one nearest to it - is complete and thus unhatched. The best images
of the end egg show what may well be the remains of a small, aborted embryo
to one side of the interior. Analysis of shell structure and mineralogy
showed that some of the eggs had not reached maturity.
(a) Note that they are much fractured and none of them is evenly rounded.
How do you think this came about?
(b) The hatchlings were obviously quite small compared with the gigantic
adult size of the parents. What does this suggest to you in terms of survival
to adulthood?
(c) In the lab. is a thin section through a piece of dinosaur egg and
another of a piece of chicken egg. Note their structure. In spite of the
obvious thickness differences, note the pores which in both cases permit
gas exchange.
(Links to the Hunterian Museum dinosaur pages, Scottish dinosaurs, Dinosaur eggs)
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As with modern organisms, fossil skeletons may show evidence of
disease or injuries. Gruesome though this may be, it is a graphical reminder
that we are dealing with once living (and dying) animals. Examine the specimens
in case 8E
Q.1. Compare the skull of the marine crocodile Metriorhynchus with the one used in the mode of life exercise. Interpret the major difference between the two.
Q.2. Examine the plesiosaur shoulder girdles. One is abnormal (the normal one is in the lab.). Describe the abnormality and deduce its likely effect on the living animal. Study of the complete skeleton of Cryptocleidus (8A) should help you.
Q.3. Examine and interpret the fragments of plesiosaur ribs in case 8E.
The Carboniferous (360-285Ma) rocks of the Midland Valley of Scotland
have recently provided several internationally important vertebrate finds.
Most of these discoveries were made by Mr Stan Wood who now makes his living
from finding, preparing and selling fossils.
Bearsden. - Major excavations in 1981-2 revealed a range of faunas and floras from the basal Upper Carboniferous rocks here. These represent both marine and non-marine environments. The results of this work were widely publicised and formed the basis for a BBC television programme ("Stan Stan the Fossils Man") and a travelling exhibition.
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Q.1. Study the specimens from Bearsden in case 4M and in the lab. and make brief notes from the associated text.
Q.2. Examine closely the specimen of Akmonistion zangerli in case 4M and the replica provided in the lab. This is the oldest known complete fossil shark. Note the gut, its contents and the coprolite ready for ejection. Describe the curious structure immediately behind the head. What function do you think this may have had?
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East Kirkton near Bathgate. - Recent finds from the Lower Carboniferous here include the earliest known reptile-like creature and superbly preserved true amphibian skeletons. The excellent preservation of complete skeletons results from the animals being smothered by ash falls. Associated deposits include hot-spring deposits - more testimony to the local volcanic activity in the region of the Bathgate Hills which you saw evidence of on the field excursion there.
Q.3. The East Kirkton 'lizard' is not only a fine specimen but also
40 million years older than any known true fossil reptile. In 1990, a German
institution offered £240,000 for it and the Royal Museum of Scotland
launched a successful public appeal for funds to purchase the fossil and
keep it in Scotland. Note the similarities to the sale of art treasures.
Ponder on the ethics of selling scientifically valuable fossils which might
be regarded as part of our national heritage. The National Heritage Fund
has so far only been used to prevent important works of art from leaving
Britain.
In case 4N are the finest known remains of a temnospondyl amphibian
from East Kirkton. These creatures were close to the ancestors of the modern
salamanders, newts and frogs. Look also at the 'Peppard's Ghost' in exhibit
10C (at the entrance of the 'Ark') which is a clever illustration showing
the relationship of the fossil remains of one of these animals to its reconstructed
corpse.
Examine the exhibits of specimens from the late Proterozoic Ediacara Fauna (case 4A) and the middle Cambrian Burgess Shale (case 4H). Why are these examples of exceptional preservation? What insights do they give us of the life of the past?
Exhibits 12A-K illustrate the evolutionary patterns leading to Homo
sapiens. Many of the points reflect general features of evolution shown
throughout the fossil record. Additional material is available for study
in the lab. (WITH CARE)
Q.1. How do fossil and modern hominid skulls compare with those of
the modern great apes?
Q.2. Can all the fossil hominid species be arranged as a single lineage
(line) of ancestors and descendants leading from Australopithecus afarensis
to H. sapiens ? If not, what patterns do they show?
Q.3. Do individual species remain constant in their range of variation
over a considerable period of time or do they show gradual changes towards
the morphology of their descendants?
Q.4. What changes in morphology can be related to changes in mode of
life?
Q.5. What other changes occurred which aren't directly apparent from
changes in morphology?
Orang-Utang |
Gorilla |
Baboon |
email Dr Neil D. L. Clark regarding the web page.
Visit the Hunterian Museum for more on hominid
evolution or fossils.
