Sunday, 27 December 2009

Comparative Studies

By looking at specific features of the fossil skeletons of pterosaurs it is possible to compare them to see how closely individuals are related. The science of comparative anatomy is limited in its application, but it is a very useful tool when dealing with fossil species. For instance - does Pterodaurstro fit more closely with the Pterodactyloids of the Rhamphorhynchoids.By looking at a comparison of wing bone lengths in relation to the wing metacarpal bone, it can be seen that the shape formed on the above graph places Pterodaustro clearly alongside that of a Pterodactyle. In many cases, the relationship of the wing bones to the wing metacarpal can be used to distinguish families of pterosaurs. However, this type of analysis should be used with caution as there are a few exceptions to the rule. Other features like skull anatomy, vertebra structure and pelvic anatomy are also needed to confirm any comparative relationships.

This graph shows the wing profile relationships between two individuals of the same species of pterosaur, found within the same sediment. The slight difference is likely due to natural variation.
Here is a wing profile graph that is generated from two unrelated pterosaurs from different sites at about the same geological age. The pterosaurs look similar in most features, but the analysis suggests significant differences in wing bone development.
When using comparators, patterns will emerge to indicate differences. Scatter graphs will often be a useful way of determining differences. The above plot shows the relationship between wing metacarpal length and first wing phalanx length in a random selection of pterosaurs. The differences between the Rhamphorhynchoid pterosaurs and the Pterodactyloid pterosaurs can be indicated by circling each group.
The final graph shows a calculated plot based on the relationship of measurements for the humerus, ulna and wing metacarpal. In this plot, there is no overlap between the two major pterosaur groups within this sample. The scales displayed are arbitrary units in the plot calculations.

Comparative anatomy is all that we can use for direct comparison of extinct fossil species. It gives a very good indication of relationships and enables structure to be developed in an evolutionary hierarchy. However, whilst this is a useful tool, it is only a guide and must be treated as such. It is often down to individual opinion as to how accurately the selected comparator work. This is why scientists develop slightly different evolutionary trees of the pterosaurs. Each may be valid within the scheme of analysis and each should be respected in that light.

Good science is all about debate and discussion but in the case of fossil analysis the picture is often quite disjointed. differences of opinion are what makes this subject interesting.

Monday, 23 November 2009

Pterosaur Eggs

Speculation about how pterosaurs reproduced has been enhanced over the years by lack of evidence. Many scientists believed that pterosaurs must have laid eggs, but were they hard shelled as in birds, or leathery as in reptiles. To some, the thought of how a long bony wing would work in an egg was a problem to imagine. Bats give birth to live young without the need for eggs, so perhaps pterosaurs could also give birth to, live young.

Speculation became analysis when, in 2004, a pterosaur egg fossil was found in China.

Avodectes pseudembryon (Wang and Zhou 2004), IVPP-v13758, was discovered in the Jehol Biota, being about 121 million years old. It was a complete embryo in a shell. The wings were coiled as they developed (sketch above) and the preservation indicates clearly that the bones were well ossified before hatching. This would enable the newly hatched pterosaurs to use the wings very quickly after emerging from the egg.

Observations of the porosity of the egg shell suggested possible burial during development and the form of the shell was soft and leathery like a reptilian egg, having a shell that was non-laminar and 0.25mm thick. The embryo wingspan was estimated to be 27cm. The bone proportions are unlike any known pterosaur, but show similarities with Anhanguera and Istiodactylus specimens. This should not be taken as an indication of species, since the bone development and proportions may have been subject to changes during juvenile life.

A second egg, JZMP-03-03-2, was somewhat similar, but the skeletal bones were not articulated in the same clear way, so interpretation is a little more complex.
In the same year, a pterosaur egg, MHIN-UNSL-GEO-v246, was discovered in the Lagarcito Formation in Argentina. This formation is well known for the Pterodaustro fossils and this egg was clearly a Pterodaustro egg. The embryo was intact and articulated.
The egg was also from the Lower Cretaceous deposits about 100 million years ago, and the proportions of the embryo closely matched those of known juvenile specimens. Measurements of the shell indicated a very thin (30μm) leathery shell which was long and oval in shape measuring 22mm by 66mm. The estimated embryo wingspan was 27cm. This egg has many differences from the Chinese finds, but it does support the idea that all pterosaurs probably laid eggs.
The questions that are difficult to resolve are;

  1. How many eggs did pterosaurs lay?
  2. Did pterosaurs care for their young?
  3. Where did pterosaurs nest and what nesting structures did they create?
I suspect that the answers to these types of questions will be different for each type of pterosaur. These creatures would have been subject to the same variations and constraints in their habitats as modern animals are subject to today.

Wang, X., and Zhou, Z., 2004, Pterosaur embryo from the Early Cretaceous: Nature, vol.429, p.621.

Chiappe, L. M., Codorniu, L., Grellet-Tinner, G., and Rivarola, D., 2004, Argentinian unhatched pterosaur fossil: Nature, vol.432, p. 571-572. (2 Dec 2004) 

Pterosaur Database Topics - eggs

Sunday, 1 November 2009

The Pterosaur Brain

In 1888, Newton published the first account of a pterosaur brain exposed in a skull from the Lias at Whitby, North Yorkshire. The skull fossil had to be excavated to reveal the exposed brain more fully. Before the work, a number of casts of the original were made and one such cast is shown below.
Perhapsicephalus purdoni, National Geographic Survey, Nottingham.

The brain fossil showed the main lobes clearly and the auditory and semicircular canal structures were identified during excavation of the skull. The analysis applied to the brain by Newton suggested that the brain of the pterosaur was in many ways similar to the brain of a lizard, but in some respects it was charactaristically similar to the brain of birds. His conclusion was that pterosaurs, birds and lizards evolved from common ancestors.

In 1941, Tilly Edinger, a German physiologist, examined two distinct pterodactyl fossils where the brain was exposed. Her findings were similar to those of Newton, but with the advantage of the intervening progress of science since the earlier investigation, Edinger was able to make a more defined conclusion about structure.
Pterodactylus elegans, MCZ, No. 1505

The pterosaur fossils that Edinger worked with had been described by several earlier and well respected German scientists, though the work that they did was descriptive and comparative. This later work looked more closely at the structures and extrapolated the knowledge to a general description of the pterosaur brain for the first time.

Developments in the brains of pterosaurs show similarities with the development of the brain in birds. These changes are attributed to the requirements of flight, with a more developed optic lobe and a fissure (Vallecula Silvii) like that found in the fore brain of birds. At this point there is no evidence for the structure of the base of the pterosaur brain.

These are the two defining works on the nature of the pterosaur brain. With the advance in medical scanning techniques, the destructive analysis of pterosaur brains is a thing of the past. It is now possible in some cases, to examine the cranial cavity of a fossil by electronic means to develop an understanding of its brain anatomy.

Newton E. T., 1888, On the skull, brain and auditory organ of a new species of Pterosaurian (Scaphognathus purdoni) from the Upper Lias near Whitby, Yorkshire. Proceedings of the Royal Society, London. 43, pages 436–440.

Edinger T., 1941, The brain of Pterodactylus. American Journal of Science. 239, 665–682.

Wednesday, 14 October 2009


The concept of evolution is based on a simple idea. If an organism can survive to pass on its genes to the next generation it is said to be fit. Fit organisms will survive best and develop into dominant or abundant species.

Charles Darwin was the scientist who published this idea in 1858 On the Origin of Species… He proposed that a small and useful change, developed in relation to the environmental conditions would lead to a change in form or behaviour that, if advantageous, would persist in the species. Such small changes would lead to evolutionary change over time. These small changes can be seen to happen is some modern day species over time.

In examining different species, Darwin observed in many cases, that the change of form was significant. He proposed the idea of modular evolution where changes happened very quickly and locally at one time, giving a change that, if advantageous, was seen as a leap forward in evolution. Over time, where the environmental conditions were stable, the form and behaviour of species would be stable and show little change. Only when a significant factor changes the conditions within a habitat would other random changes become more advantageous. This concept is difficult to observe in reality, but it does rationalize the changes seen in fossils.

A recent find from China, Darwinopterus modularis, demonstrates this concept quite well. This is an advanced pterosaur in many features, but it has retained the long tail of the early pterosaurs. This species helps to link the changes between the Rhamphorhynchoidea and the Pterodactyloidea.

This pterosaur has been placed in a group called the Monofenestrata, which includes Darwinopterus and also encompasses all of the Pterodactyloidea.

Darwin C R, 1859, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. London, John Murray.

Lu J, Unwin D M, Jin X, Liu Y and Ji Q., 2009, Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull, Proceedings of the Royal Society B., Published online before print October 14, 2009, doi: 10.1098/rspb.2009.1603

Proceedings of the Royal Society B - October 2009

Saturday, 3 October 2009

The Problem With Ornithocheirus

The Ornithocheiridae are a group of large pterosaur fossils from the Cretaceous. They represent several distinct species and most are known only from fragmentary remains of jaws or bone joints. In many cases it is not clear which bones belong to which jaws.
In the late 1800's, this group of pterosaurs was represented mainly by remains in the Sedgwick Museum, Cambridge and the British Museum of Natural History (Now the Natural History Museum, London). The classification was a dumping bin for any pterosaur material from the Cretaceous that were not easily placed in an existing structural hierarchy. Many of the specimens were attributed to the work of Richard Owen or Harry Seeley.

This problem arose from specimens collected from the Cambridge Greensand. The specimens were deposited within the Greensand from elsewhere, perhaps from moving sediments or as fossils eroded from other rocks and re-deposited. In many cases, the age and location of the original deposition is unknown.
It has long been accepted that the Ornithosaur fossils represent a wide range of species that may well be unrelated. With little evidence of accociations, the work to sort the fossils out has not been done. Some time ago, David Unwin made a brave attempt at sorting out the problem and was successful in pulling some specimens out of the Ornithcheirus group, but with limited evidence, the problem will not be resolved easily.
Above is a sketch of a lower jaw fragment of Ornithocheirus fittoni, showing the staggered tooth pattern which is unusual amongst pterosaurs
Ornithocheirus sedgwickii shows a very different tooth pattern on its lower jaw. It may be that these specimens have enough similarities to place them in the same family group. If more was known about the rest of the skeletal remains, then a clearer perception would lead to a better conclusion. There are many more Ornithocheirids. Should they remain associated until such a time as there is more available fossil evidence. I personally do not have a problem with the idea of a dumping bin for odd bits and peices of remains. Science is full of problems and grey areas, so some means of containing these problems within a classification system is not a bad thing. The process often works well when a new specimen is found. You can take a look in the dumping bin from time to time and see if anything starts to look familiar.

Bowerbank J. S., 1851, On the Pterodactyles of the Chalk Formation. Proc. zool. Soc. Lond.,
pp. 14–20 & Ann. Mag. nat. Hist.(2) 10, 372–378.

Fritsch A. & Bayer F., 1905 Neue Fische und Reptilien aus der böhmischen Kreideformation.
Prague, privately published. pp. 30–32 & pl. 8

Newton E. T., 1888, Notes on pterodactyls. Proc. Geol. Ass. Lond. 10, 406–424.

Owen R. & Bowerbank J. S., 1852, On a new species of pterodactyle (Pt. compressirostris,
Owen) from the Chalk. Ann. Mag. nat. Hist. 10, 372–391.

Owen R., 1859 On remains of new and gigantic species of Pterodactyle (Pter. fittoni and Pter. sedgwickii) from the Upper Greensand near Cambridge. Rep. Br. Ass. Advmnt Sci. 28 (1858), 98–103.

Seeley H. G., 1870, The Ornithosauria: an elementary study of the bones of pterodactyls,
Proceedings of the Cambridge Philosophical Society, 2(1870) p.186

Seeley H. G., 1876, On the organisation of the Ornithosauria. J. Linn. Soc. Lond. Zool. 13, 84–

Unwin D. M., 1991, The morphology, systematics and evolutionary history of pterosaurs from the Cretaceous Cambridge Greensand of England, University of Reading (Unpublished), Ph.D. Thesis

Wednesday, 16 September 2009

Pterosaur skeletal sculptures

Bruce Mohn is a comparative anatomist, palaeontologist and Palaeo-Sculptor with a specialism in mesozoic vertebrates. He has recently completed skeletal models of pterodactylus and rhamphorhynchus for the Carnegie Museum and the quality of his work is outstanding.
The model components are crafted from observations of fossil material and investigative techniques to give a realistic life-like shape to each individual component of the skeleton. The assembly of the individual components uses wired supports to give an accurate representation of the complete skeletal structure of the animal. This technique allows the skeleton to be wired into any orientation or possition that was possible in life.
If you are able to visit the Carneige Museum, it is worth finding these skeletal models to view the 3D structure of these pterosaurs, which cannot be fully appreciated from diagrams.

Bruce is able to make bones or skeletons to order - this is fine bespoke craftsmanship of the best museum quality. His work can be seen at - Bruce Mohn sculptures at Dinoart

Bruce Mohn

Carnegie Museums

Monday, 24 August 2009

Belemnite Ink Reconstituted

Recently, Dr Phil Wilby and his team were working to extract well preserved remains from a site near Christian Malford in Wiltshire for the British Geological Survey. The outcome of this extensive dig was to recover specimens of belemnite ink which has been reconstituted and used to write with.

This work mirrors the work of Joseph Anning in 1828 when he drew an illustration of a fossil skull of Dimorphodon macronyx using reconstituted belemnite ink from the Jurassic specimens found near Lyme Regis in Dorset.

The new work is significant insofar as it will allow the ink from the Wiltshire specimens to be analysed in detail - something that has not been done before.

The specimens used were classified as Belemnotheutis antiquus and were younger than the Anning Specimens. The ink was reconstituted in the same manner by adding ammonia to liquefy the solid ink sac contents.

The article in The Times reports that - "The specimen is now in the British Geological Survey collection in Nottingham. Part of the ink sac has been sent to Yale University in New Haven, Connecticut, for more detailed chemical analysis. "

Mary Annings Pterodactyle

The Times - 19 August 2009 Article by Simon de Bruxelles

The Times - 22 August 2009 Dave Martill's Comment

Saturday, 15 August 2009

Pterodactyls Alive in 1985

In 1985 the BBC broadcasted an edition of the popular series "Wildlife on One" entitled Pterodactyls Alive. The centrepiece for this program was a dynamic model of Dimorphodon macronyx, nicknamed Didi.
The model was made by Arril Johnson and was commissioned by Aardman Animations in July 1984 as an animation model for the series. The model was made after consulting the leading experts of the day. Kevin Padian, curator of the Museum of Paleontology at the University of California at Berkeley and Hugh Aldridge a bat flight researcher at Bristol University who both contributed ideas to the modelling process.
This interesting model now resides in a display at the Bristol City Museum and Art Gallery on Queens Road, Bristol, UK. It is worth a visit if you are in that part of the world.
These two photographs are mood shots taken by Arril Johnson before the model was handed over to Aardman for the filming of the program content. Both pictures are copyright of Arril Johnson and used with permission. The images are to be included in a rewrite of the Bristol City Museum page on the Pterosaur Database website in the near future.
It is work like this that stimulates discussion in pterosaur research. Kevin Padian proposed ideas about the morphology and locomotion of Dimorphodon which were a little slow to be accepted in some areas. Modelling like this helps to demonstrate the practicality of such suggestions and put these kinds of ideas into context.

Aldridge, H; 1986. Manoeuvrability and ecological segregation in the little brown (Myotis lucifugus) and Yuma (M. yumanensis) bats (Chiroptera: Vespertilionidae). Canadian Journal of Zoology 64:18781882.

Johnson A; 1986, Didi a model with a difference, The Geological Curator Vol 4 ,No 5 page 289-290, September 1985.

Padian K; 1983, Osteology and Functional Morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla (Peabody Museum of Natural History), No.189, 1-44.

Monday, 10 August 2009

Park Hall Country Park

In 1985, Steven Winkworth made the first large scale flying model of Pteranodon, which he flew over the Dorset Coast. The model was used in the BBC television program - Pterodactylus flies. This event was published in New Scientist and in the national newspapers of the time, but outside of the world of pterosaur enthusiasts it is not a well known event.
This weekend I walked at Park Hall Country Park in Staffordshire. Having popped into the visitor centre for an ice cream I was confronted by a painting of the Steven Winkworth flying model on the wall in front of me.
The painting was done by Christopher Guest some 5 years ago, when he worked for the Community Art Team of Stoke-on-Trent City Council, run by Paul Bailey. The wall painting is quite a faithful representation of the model, as can be seen from the photographs. What an unusual find!
This small exhibit room boasts quite a few pterosaurs, like these Quetzalcoatlus soaring in the skies, perhaps over Stoke - who knows.

Park Hall is a site of special scientific interest for its glacial deposits and bedded gravels, as well as having a wide range of different biological habitats in close proximity. Not a place where you would expect to find Pterosaurs.

Winkworth S., 1985, Pteranodon Flies Again, New Scientist, 3 Jan 1985: p32-33.

Winkworth S., 1985, Pteranodon, Flug und Modelltechnik, 359, p990-993. Verlag fur Technik und Handwerk, Baden-Baden.

Sunday, 2 August 2009

Resolving Criorhynchus

In 1861, a new species of pterodactyl was published by Richard Owen. The specimen was the end of a snout with a couple of teeth and 5 tooth sockets. He called this specimen Pterodactylus simus. A few years later he assigned the specimen to a new genus Criorhynchus simus. Harry Govier Seeley also published the specimen as Criorhynchus simus and added other specimens of anterior jaw fragments to this genus.

Several upper jaw snouts were discovered from the Upper Greensand. This is a derived deposit which contains lots of fragmentary remains. The nature of this pterosaur was not well known and analysis of the remains were very speculative at the time.

With no associated remains Criorhynchus was just a series of similar snouts. For many years the consensus was that this was a short snouted large pterosaur with a solid jaw and a very powerful bite.

It was not until 1987 when Peter Wellnhofer described a specimen from Brazil which he called Tropeognathus mesembrinus. This was one of those inspirational discoveries which put the Criorhynchus specimens into context. These species were interpreted as skim feeders with an aqua dynamic snout tip crest.
With increasing fossil evidence, this specimen was later re-assigned to the genus Anhanguera by Kellner and Campos in 1989.

Many pterosaur finds tend to follow this pattern of discovery and rediscovery. This is how science works. There are draws full of unassigned pterosaur specimens in museums around the world waiting for that magic moment when someone makes a discovery or a link that helps to put them into their correct context. Finding such resolutions is a joy.

Owen, R. 1861 Monograph on the fossil Reptilia of the Cretaceous Formations. Supplement III. Pterosauria (Pterodactylus). The Palaeontographical Society, London. (volume for 1858; pp. 1–19 & pls 1–4)

Owen, R. 1874 A Monograph on the Fossil Reptilia of the Mesozoic Formations. 1. Pterosauria. The Palaeontographical Society, London. pp. 1–14 & pls 1–2.

Wellnhofer P; 1987, New Crested Pterosaurs from the Lower Cretaceous of Brasil, Mitteilungen der Bayerischen Statssammlung fur Paleontologie und historische Geologie, 27: 175-186 Munchen

Kellner, A. W. A. & Campos, D. de A. 1990, Preliminary description of an unusual pterosaur skull of the Lower Cretaceous from the Araripe Basin. Atas I. Simp. sobre a Bacia do Araripe e Bacias Interiores do Nordeste, pp. 401–405.

Sunday, 26 July 2009

Was Rhamphorhynchus a skim feeder?

Whilst translating a passage from Peter Wellhofers' work on the Rhamphorhynchoidea, I came across this specimen from the collection of Karl Strobl.

Specimen No. 28: Fig. 24; Plate. 8, Fig. 1-3. Wintershof. Sammlung KARL STROBL, Eichstätt.
Part and counterpart of an entire skeleton with excellent preservation.

The individual is seen from the side; the arms are pushed forwards, the flight fingers in parallel with backbone extend backwards. Impressions of the flight skin and the narrow, lance shaped tail sail are present. The lower jaw extremity is relatively high, blunted in front. The upper edge line of the skull is concave. The front edge of the Infra-temporal opening is formed by the Quadrato-jugale. The cranial length measures 55.5mm.
The gastral skeleton consists of 6 curved bones still in situ; the middle pieces are displaced forwards. The Pubis is widened ventral, so that to the Ischium appears as a bay than rather a round opening. The Prepubis is strengthened centrally and hook-shaped (fig. 10 e).
Within the body cavity is a compressed fish tail and numerous single fish bone fragments indicating the stomach contents. Beside this lies 6-7mm long bananas-shaped small sausages like gastric stones of 1.5mm diameter and with zigzag-shaped textured surface (ref. fig. 44 b).

This specimen clearly shows that this individual had eaten a fish which was swallowed whole, head first. The use of gastric stones to aid mechanical digestion is an indication of a more specialised digestive system. This rhamphorhynchus may have had a gizzard, similar to that seen in birds, or a muscular and thick stomach wall to enable the churning of contents to allow the enzymes and gastric stones to break down the food both chemically and mechanically.

Very few pterosaurs give information about stomach contents, and in this case it leads to a question about fishing methods. Did rhamphorhynchus use a surface skimming technique to fish, or was it a shallow diver. It is impossible to say for certain, but the evidence is compelling. The jaws would certainly be able to scoop up a fish from near the surface of the water. and such a technique would have needed a very precise flying skill and good control of the jaws and neck.

The jaw on this specimen shows an impression of an upturned bony sheath at the end of the lower jaw. Such a structure, being free of teeth, would lend itself to surface skimming. This is a strong clue to the feeding habits of this type of Rhamphorhynchus and the group as a whole.

Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil II. Systematische beschreibung. Paläontographica A 148, 132–186.

Sunday, 19 July 2009

The Rhamphorhynchoidea

In 1975, Peter Wellnhofer wrote a classic monograph on the Rhamphorhynchoidea. This set of 3 linked works has been the baseline for the study of this group of pterosaurs since then. It is a well organised work with analysis split into skeletal morphology, systematics and Palaeoecology. The texts were originally in German and as far as I am aware, they have not been translated wholesale into English. Recently, I started to translate part 2 for my own use. I would love to publish my translation, which will be a new work, but the original text is not out of copyright until 2025. I can only find paper copy, but I have been told that there is an electronic copy in German. This has eluded me, so I am transcribing and translating from the original text.

Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil I. Allgemeine Skelletmorphologie. Paläontographica A 148 , 1–33.11 plates.

Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil II. Systematische beschreibung. Paläontographica A 148, 132–186.

Wellnhofer, P. 1975 Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Teil III. Palökologie und Stammesgeschichte. Paläontographica A 149, 1–30. 13 plates

The problem in translating any text is the transfer of meaning. There are words in German that can have several possible meanings in English. This also works the other way around. The bulk of the meaning is transferable with a high level of confidence in the result, but there are some areas where the meaning has to be a best guess. This type of translation is often referred to as a Gist Translation. This means that in some cases, the reader may need to refer to the original text to grasp the full meaning of a sentance of passage. It is for this reason that translations should only be attempted from the original documents. Another of Peters texts that I have frequently used is the Handbook of Paleoherpetology, Part 19. This text is also only available in German, so people who are not able to read that language can only look at the wonderful line drawings and be amazed. This is of course, another text that sets the baseline for the study of pterosaurs in general. It is a little dated now, but still a valuable resource. The original text is still available to purchase on the Internet.

Wellnhofer, P. & Khun, O. 1978 Handbuch der Paläoherpetologie. Teil 19. Pterosauria. Stuttgart: Verlag Gustav Fischer.

These texts defined the study of pterosaurs for a whole generation of researchers. It would be beneficial to the subject to have them available on line both in their original German text and in English. The main difficulty is in gaining permission to freely allow access without infringing copyright law. Watch this space!

Tuesday, 7 July 2009

The Frog Mouthed Pterosaurs

Anurognathus ammoni, a pterosaur from the upper Jurassic Solenhofen limestones of Bavaria, was first published in 1923 by Dodderlein. This was recognised as a very unusual small pterosaur, having a very broad and short jaw. Nothing had been seen like this before. The specimen was poorly preserved and the bones were somewhat disarticulated, but the animal clearly has short blunt teeth which were not suited to tearing flesh. "Frog Jaw" was thought to be an insectivore, possibly catching is prey on the wing or on leaves and branches around forested areas.
A second, well articulated specimen of
Anurognathus ammoni was described by Bennet in 2002 and this specimen shows the skeletal anatomy of the pterosaur very clearly.
Another frog mouthed species,
Batrachognathus volans, is known from the Karatau Mountains, Upper Jurassic sediments of Kazakhstan. This species was described by Rjabinin in 1948. The specimen is a partial skeleton including a disarticulated skull which clearly shows a wide jaw. This specimen shows some similarities with Anuroghnathus, but enough differences to classify it as a different species.
Dendrorhynchoides curvidentatus is a Tithonian species that was collected from the Chaomidianzi Formation, Zhangijagou locality from the Lower Yixian Formation near Beipiao City, Western Liaoning Province, China. It was published in 1998 and is one of several fine specimens to come out of this part of China. This is a very good fossil of this type of pterosaur and it has been restored after a preparator doctored the fossil in an attempt to make it more salable.
Jaholopterus ninchengensis is a compete Anurognathid with some soft part preservation from the Lower Yixian Formation at Nincheng, Inner Mongolia. This specimen is known as the Nincheng Rehe Pterosaur and is in the Institute of Vertebrate Paleontology and Paleoathropology in Beijing. The specimen caused quite a stir when it was published in 2002.

These 5 specimens are the major contingent of the classification Anurognathidae. There are a few fragmentary remains, like a jaw fragment from the Middle Jurassic Stonesfield Slate which is in The National Museum of Wales, Cardiff. The Anurognathids were probably quite widespread in distribution, but I suspect that they were forest dwelling pterosaurs, living in places where fossilization is a rare process. The scientific community is probably quite lucky to have this many specimens of this pterosaur lineage to work with.

Döderlein L., 1923, Anurognathus ammoni, ein neuer Flugsaurier. Sitzungsberichte der Bayerischen Akademie Wissenschaften, math.-naturwiss. Klasse, 1923, München. Pp. 117- 64, figs. 1-7.

Bennett S. C., 2002, A second specimen of Anurognathus from the Solnhofen Limestone of South Germany. Journal of Vertebrate Paleontology 22 (supp. 3), 36A

Rjabinin A. N., 1948, Remarks on a flying reptile from the Jurassic of the Kara-Tau, Akademia Nauk, Paleontological Institute, Trudy, 15(1): 86-93, 1 plate, Moscow and Leningrad.

Ji S.-A. and Ji Q., 1998, A new fossil pterosaur (Rhamphorhynchoidea) from Liaoning. Jiangsu Geology 22(4): 199-206.

Wang X., Zhou Z., Zhang F. and Xu W., 2002, A nearly complete articulated rhamphorhynchoid pterosaur with exceptionally well-preserved wing membranes and "hairs" from Inner Mongolia, Northeast China. Chinese Science Bulletin vol. 47(3), pp. 226-232.

Tuesday, 30 June 2009

A very Peculiar Pterosaur

Pterodaustro is represented by a number of specimens from Argentina. There is a complete skeleton, a partial juvenile and an egg, just to mention a few. This unusual pterosaur is quite well represented in the fossil record, certainly enough is known to make a convincing reconstruction.
Most unusually, this was a filter feeder with a fine sieve of unusually adapted teeth that would have been ideal for filter feeding on small aquatic living organisms. This was the Flamingo of the ancient world!
The diagram of the skull shows the peculiar nature of this animals jaw. This pterosaur has more teeth than any other pterosaur. It is likely that it has more teeth than any other Dinosauromorph. It is also the first pterosaur where gizzard stones have been observed to be present.

The holotype, which was originally described by Bonaparte, is PLV 2571 and is a right humerus in the Institute Miguel Lillo, Universitat Nacional Tucuman, Argentina. Most of the specimens come from South America which is probably where the species evolved within a specific shallow water habitat, where zooplankton and phytoplankton were abundant.

In 2004 un-hatched egg containing a juvenile Pterodaustro, from the Lagarcito Formation in Central Argentina was described. The lacustrine deposits in which it was found are called the Loma del Pterodaustro and they are dated to about 100 million years ago. The specimen MHIN-UNSL-GEO-V 246 has been studied using electron micrographs of the egg shell suggesting a leathery shell. Ghosting of proteins can be interpreted within the shell structure which has yealded a significant amount of information about this pterosaurs eggs.

Bonaparte J F, 1970 Pterodaustro guinazui sp.nov.. Pterosaurio de la formacion Lagarcito, Provincia de San Luis, Argentina, Acta Geologica Lilloana, 10(10):207-226

Bonaparte J F, 1971 Descripcion del craneo y mandibulas de Pterodaustro guinazi (Pterodactyloidea - Pterodaustriidae), de la Formacion Lagarcito, San Luis, Argentina, Publ. Mus. Mun. Cienc. Nat. Mar del Plata, Pp. 63-272

Bonaparte J F & Sanches T M, 1975 Restos de um Pterosaurio,Puntanipterus globosus de foracion la Cruz, provincia de San Luis, Argentina, Actas Primeiro Cong. A

L. M. ChiappeA. Chinsamy, 1996, Pterodaustro's true teeth, Nature 379, 211 - 212 (18 January 1996)rgentino Paleont. Biostretigr., 2:105-113

Frey E., Martill D. M., Chong-Diaz G. and Bell M., 1997, New pterosaurs from the Lower Cretaceous of Chile. J. Vert. Paleont. 17 (3)

Codorniú L, Chiappe L.M. Early juvenile pterosaurs (Pterodactyloidea: Pterodaustro guinazui) from the Lower Cretaceous of central Argentina. Can. J. Earth Sci. 2004;41:9–18

Chiappe L.M., Codorniú L., Grellet-Tinner G. and Rivarola D., 2004, Palaeobiology: Argentinian unhatched pterosaur fossil, Nature. 432, pp. 571-572 (2 Dec 2004)

A Chinsamy, L Codorniú, and L Chiappe, 2008, Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guiñazui, The Royal Society, Biol Lett. 2008 June 23; 4(3): 282–285

Saturday, 20 June 2009

Mary Annings Pterodactyle

On 21st May 1799, Mary Anning was born, daughter of Richard and Mary Anning of Lyme Regis, Dorset, England. During her life she collected curiosities from the beach at Lyme Regis and nearby coastal areas. She became a very proficient and knowledgeable collector of fossils and made a number of remarkable discoveries. She often referred to experts for advice and support and her main sources were William Buckland, Henry de la Beche and William Conybeare, who were able to develop their reputations on many of Mary's discoveries.
In 1828, Mary discovered a fossil pterodactyle (later named Dimorphodon macronyx) which she discussed with William Buckland. Buckland wrote a paper on this fossil and it was known to be the finest of the English pterodactyles. The remains are now in the Natural History Museum, London.
Shortly after the discovery, her brother Joseph made a sketch of the fossil skull. He used reconstituted belemnite ink from the finds on Lyme Regis Undercliff. This drawing is now held by the Philpot Museum, Lyme Regis - though neither the fossils or the sketch are on display as they are considered too valuable to be exposed to the public.
The remaining bones of the fossil find were almost a complete skeleton and an additional find revealed the whole of the animals tail. This was one of the few pterosaurs that enabled a complete reconstruction to be attempted. A second skeleton and skull (minus tail) gave a better insight into the association of the bones and over the years, several small bone finds have been made. Many of these are in private collections.

Thackray J. C. A., 1995, A catalogue of portraits, paintings and sculpture at the Natural History Museum London. Mansell: London. xii, 70pp.

Torrens H. S., 1995, Mary Anning (1799-1847) of Lyme : ‘the greatest fossilist the world ever knew’. British Journal for the History of Science, Vol. 28, pp.257-284.

Buckland W. 1829, On the discovery of a new species of pterodactyle in the Lias at Lyme Regis. Trans. geol. Soc. Lond. ser. 2, 3, 217–222, pl. 27.

Padian K, 1983, Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea). Based on new material in the Yale Peabody Museum. Postilla 189.
Pierce P., 2006, Jurassic Mary, Mary Anning and the Primeval Monsters. Sutton Pp238.

Monday, 15 June 2009

Discovering Pterosaur flight - Part 2

The design of Flying model pterosaurs was taken a stage further in 1957 when Erich von Holst made a flying model of Rhamphorhynchus. This model was powered by a coiled elastic band which was connected to a rocker device which flapped the wings of the model. The tail sail had to be horizontal to stabilise the model in flight. From this experiment it was clear that the Rhamphorhynchus form had the potential to be a very good flying animal.

In the 1970's a bat expert (Cherrie Bramwell) and an engineer (R G Whitfield) teamed up to examine and analyse the joints of large pterosaurs. They defined the range of movement in the wing joints and proposed a postural model for Pteranodon. G R Whitfield had flown a fully controlled life size model in 1973, but that model was eventually destroyed in a crash landing. This work was an extension of the Hankin and Watson work and was to provide a basis for future flying models.
Stephen Winkworth was a model aeroplane builder who had an interest in anything that flies. In 1984 he designed a pterosaur flying model, based on the Bramwell and Whitfield work which was flown in January 1985 on the cliffs along the Dorset coast. The model was filmed for the BBC television production "Pteodactylus Flies". This 15 foot wingspan model was an excellent radio controlled glider, though to overcome some stability problems, additional stability fins had to be incorporated in the design.  

The Quetzalcoatus Project was started in 1984 and in December1985 Paul MacCready flew a half size flying model of Quetzalcoatlus. This flying model was much more sophisticated than the balsa and fabric model of Stephen Winkworth and used aviation technology for its construction. It had an autopilot device and a recovery parachute which could be controlled from the ground. The project was used to produce an IMAX movie in 1986 for the Smithsonian Air and Space Museum in Washington D. C.

Up to this point, the flying models of Pterosaurs had all been gliders or simple flapping models, using aeroplane aerodynamic theory in their production. The Stanford Project, which was supported by National Geographic was intended to build a flying model that worked like a real animal. This was an ambitious project and had an extensive team headed by Margot Gerritsen. The model flew in many forms, first taking to the air in 2006 with a stabiliser tail boom to allow the electronic movements to be tested. The model was air lifted and launched at altitude by a carrier plane. The Stanford model was nicknamed Herki and featured in the TV program "Sky Monsters", which is now available on video.

What next?......

Holst E. von.,
1957, Der Saurierflug, Paleontologische Zeitschrift, 33, pp. 15-22. 7 figures.

Bramwell C. D. & Whitfield G. R., 1974, Biomechanics of Pteranodon. Philosophical Transactions of the Royal Society, London, B.267, pp.503-581

Winkworth S., 1985, Pteranodon flies again. New Scientist, 3 January 1985:32-33

MacCready P,, 1985, The Great Pterodactyl Project. Engineering and Science, November 1985: 18-24

Wednesday, 10 June 2009

Discovering Pterosaur flight - Part 1

In the early days of research, Samuel Thomas von Soemmering made the first sensible reconstruction of a pterosaur skeleton in 1812. The reconstruction was missing several skeletal elements, but was a sound model based on the available evidence. He also proposed a wing membrane form which, although too generous in area was a good attempt at theoretical reconstruction.
It was not until 1882 that the wing structure was known from the fossil record. A specimen originally named Rhamphorhynchus phyllurus was discovered in the Lithographic Shale of Bavaria. At about the same time an isolated wing known as the Zittel wing (above) was published. Both fossils showed the outline and structure of the wing membrane of Rhamphorhynchus. This enabled much better reconstructions to be made.

In 1910 C. F. Eaton produced a paper on the osteology of Pteranodon with a skeleton reconstruction This was an inspired paper showing the skeletal form of a large pterosaur. Pteranodon was only known from crushed and distorted remains and this paper showed the skeletal form in a realistic way.

Ernst Stromer was inspired by the Rhamphorhynchus wing membranes and he produces a flying glider in 1913 which demonstrated that Rhamphorhynchus could fly with the known wing form.

By1914 the Hankin and Watson paper on the flight of Pteranodon gave us an insight into the structure of large pterosaurs that was related to the way they could fly. The framework was set for some real flying models.

Watch this space.......

von Soemmerring, S. T. 1812 Über einen Ornithocephalus oder über das unbekannten Thier der Vorwelt, dessen Fossiles Gerippe Collini im 5. Bande der Actorum Academiae Theodoro-Palatinae nebst einer Abbildung in natürlicher Grösse im Jahre 1784 beschrieb, und welches Gerippe sich gegenwärtig in der Naturalien-Sammlung der königlichen Akademie der Wissenschaften zu München befindet. Denkschr. k. bayer. Akad. Wiss. math.-phys. Kl. 3, 89–158, plates.

von Zittel, K. A., 1882, Über Flugsaurier aus dem lithographischen Schiefer Bayerns. Paläontographica 29, 47–80 & pls 10–13.

Eaton, G. F., 1910, Osteology of Pteranodon. Mem. Conn. Acad. Art. Sci. 2.pp.1-38.

Marsh, O. C., 1882, The wings of Pterodactyles. Am. J. Sci. (3)23, 251–256 & pl. 3

Stromer E., 1913, Rekonstruktionen des Flugsauriers Rhamphorhynchus gemmingi, H. v. M., Neues Jahrb. Min. Geol. Pal., II, pp. 49-68.

Hankin E. H., & Watson D. M. S., 1914, On the flight of pterodactyls. Aeronautical Journal 18, 324–335.

Tuesday, 2 June 2009

The Origin of Pterosaurs

Where did pterosaurs come from? This has been a question that scientists have considered for a long time.
It is clear from the skull of pterosaurs that they belong to a group of reptiles called the Diapsids. This just happens to be the biggest group of reptiles that there is. This group is classified on the basis of individuals having a pair of openings in the back of the skull. It can be seen in the sketch of Eudimorphodon, a very early pterosaur, that there are two openings behind the orbit. There is also a sclerotic ring within the orbit.

Another feature of early pterosaurs is their tricuspate teeth. Later pterosaur teeth are single cusped. These features link the pterosaurs to basal dinosaur groups, making them Dinosauromorphs. This is still a very big group to pin them down within.

The problem with trying to examine pterosaur origins is a complex one. Firstly, the earliest pterosaurs that are recorded in the fossil record are very well adapted for flight. Their bone shape and structure have significantly changed with adaptations for flight, being thinner, lighter and structurally strengthened. These changes cannot easily be reconciled with an ancestral form. Secondly, pterosaurs are limited in their adaptation by the physical requirements for flight, so any evolutionary changes tend to have a convergent element. Similar wing shapes, structures and balance are needed to be able to compete and survive.

Pterosaurs had air sacs and flow through lungs, similar to those found in birds and in some dinosaurs. It seems likely that these structures developed only once in these animals and they had common ancestors. The most likely candidate for this ancestry would be within the Ornithodirs. This is a view supported by several researchers.

It is likely that the pterosaur ancestors evolved as a small isolated community in a localised area of the world. It may be that the habitat did not produce fossils easily (erosional environment) or that any sediments holding such fossils have not yet been found. It may also be the case that the sediments containing such fossils have been eroded away in the recent past. Whatever the reason, the elusive missing link has not been found.

Of course, the other factor in the equation is the choice of characteristics to compare when looking for an ancestral species. Depending upon which characters are given dominance, different conclusions can be made. For instance, if you classify based on neck structure, the pterosaurs are more likely to seem like Archosauromorphs. If the dominant characteristic is the foot, then they come out ar Dinosauromorphs. At present, there is not enough evidence to identify an ancestral species and make the link back to any specific group. Ornithodire ancestry is just a best guess based on sound, but incomplete, evidence.

Padian K., 1984, The Origin of Pterosaurs, Third Symposium on Mesozoic Terrestrial Ecology, Pp.163-168 Tubingen, Attempto Verlag

Bennett S. C., 1996, The origin of pterosaurs and their systematic position within the Diapsida. Journal of Vertebrate Paleontology, 16; Sup.3

Hone D. W. E. and Benton M.J., 2007, An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles, Journal of Systematic Palaeontology, 5: 465-469.

Claessens L. P. A. M., O'Connor P. M. and Unwin D. M., 2009, Respiratory Evolution Facilitated the Origin of Pterosaur Flight and Aerial Gigantism. PLoS ONE 4(2): e4497. doi:10.1371/journal.pone.0004497