kovish@winston.UUCP (Barrie Kovish) (10/02/85)
[]
Here is a question and a proposal regarding "flying"
reptiles in the mesozoic (?). First the proposal.
I have seen parts of a debate as to weather some of the
larger reptiles could fly or were only gliders. Most
of the arguments seem to assume that the reptiles
either were carion eaters or ate fish. Both of these
seem some what unlikely if the organisms were only week
gliders. My suspicions are that these organisms could fly
much better than we think. However there is another possibility
albeit somewhat bizzare.
Maybe these large flying reptiles were filter feeding plankton eaters!
I am using the word plankton to indicate small airborn organisms
probably insects. I suspect there is good anatomical reasons not
to believe this, however fossil remains are typically far from complete.
There are several reasons to believe this proposal is possible.
1. There are known examples of avian plankton eaters today. The frogmouths
(birds) which attract insects into their mouths by pheromones.
2. There certainly no shortage of marine plankton eaters. They are all
slow swimmers. Hence by symetry an airial plankton eater should be a
week flier.
3. A plankton eater would not have to land very often. Possibly only to
breed. There are I beleive some species of marine birds which stay aloft
for years at a time.
4. Reptiles require less energy per unit mass. Hence a lower density
of insects is needed to support a reptilian plankton eater than an
avian one.
5. Point 4 again only gliders require less energy than fliers. Hence even
a lower density of energy is required.
6. Insect eating is certainly one of the main preoccupations of
modern fliers such as Bats, Birds and Insects.
So now the question.
If the above is not true who was eating all the flying insects I suspect
were quite abundant in the mesosoic?
Is there anyone out there with a good enough memory to comment?
--
Barrie Kovish
New Media Technologies
..decvax!microsoft!ubc-vision!winston!kovish
..ihnp4!alberta!ubc-vision!winston!kovishethan@utastro.UUCP (Ethan Vishniac) (10/06/85)
> [] > 4. Reptiles require less energy per unit mass. Hence a lower density > of insects is needed to support a reptilian plankton eater than an > avian one. Since some pterosaurs have been found which show impressions of hair (or something like it) on their bodies the implication is that they were warmblooded. Cold blooded animals are unlikely to have insulation since they rely on the sun to raise their body temperatures. If this is the case then pterosaurs did not have "reptilian" metabolisms and comments like the above are suspect. -- "Superior firepower is an Ethan Vishniac important asset when {charm,ut-sally,ut-ngp,noao}!utastro!ethan entering into ethan@astro.UTEXAS.EDU negotiations" Department of Astronomy University of Texas
friesen@psivax.UUCP (Stanley Friesen) (10/07/85)
In article <148@winston.UUCP> kovish@winston.UUCP (Barrie Kovish) writes: >[] > >Here is a question and a proposal regarding "flying" >reptiles in the mesozoic (?). First the proposal. > >I have seen parts of a debate as to weather some of the >larger reptiles could fly or were only gliders. Most >of the arguments seem to assume that the reptiles >either were carion eaters or ate fish. Both of these >seem some what unlikely if the organisms were only week >gliders. My suspicions are that these organisms could fly >much better than we think. However there is another possibility >albeit somewhat bizzare. > No one has ever said that Pteranodon and Quetzalcoatlus were *weak* gliders. Have you ever seen an Albatros fly? They are hardly *weak* gliders, since they *rarely* flap their wings and yet can stay in the air for *days* on end and go where they wish. The model for the large gliding pterosaurs is based to a large extent on the Albatros, which *is* a glider and *is* a fish eater. Similar considerations apply to carrion eating gliders, such as modern large vultures. Note that it is not strictly *size* which is significant, it is wing structure. Gliders have long thin wings *relative* to body size, active flyers have relatively shorter, broader wings. -- Sarima (Stanley Friesen) UUCP: {ttidca|ihnp4|sdcrdcf|quad1|nrcvax|bellcore|logico}!psivax!friesen ARPA: ttidca!psivax!friesen@rand-unix.arpa
friesen@psivax.UUCP (Stanley Friesen) (10/07/85)
In article <148@winston.UUCP> kovish@winston.UUCP (Barrie Kovish) writes: >[] > >Maybe these large flying reptiles were filter feeding plankton eaters! >I am using the word plankton to indicate small airborn organisms >probably insects... >There are several reasons to believe this proposal is possible. > >1. There are known examples of avian plankton eaters today. The frogmouths > (birds) which attract insects into their mouths by pheromones. Rather a rare type of adaption, and more closely related to the Angler Fish feeding mechanism than to marine plankton eating. > >2. There certainly no shortage of marine plankton eaters. They are all > slow swimmers. Hence by symetry an airial plankton eater should be a > week flier. > >3. A plankton eater would not have to land very often. Possibly only to > breed. There are I beleive some species of marine birds which stay aloft > for years at a time. > >4. Reptiles require less energy per unit mass. Hence a lower density > of insects is needed to support a reptilian plankton eater than an > avian one. > >5. Point 4 again only gliders require less energy than fliers. Hence even > a lower density of energy is required. > >6. Insect eating is certainly one of the main preoccupations of > modern fliers such as Bats, Birds and Insects. > Well, this sounds very nice and logical, the flaw is that insects(your airial plankton) are themselves *active* flyers rather than passive like marine plankton. Also observation of modern insectivorous birds which eat "on the wing" shows that they are *without* *exception* small, fast, active flyers(flycatchers, nighthawks &c). (The Frogmouth eats while *perched*). >So now the question. >If the above is not true who was eating all the flying insects I suspect >were quite abundant in the mesosoic? > The small, fast, active-flying pterosaurs like Pterodactylus, Rhamphorhynchus and thier kith and kin rather than the large gliders. Just because *some* of the forms were large and "slow" doesn't mean they all were. -- Sarima (Stanley Friesen) UUCP: {ttidca|ihnp4|sdcrdcf|quad1|nrcvax|bellcore|logico}!psivax!friesen ARPA: ttidca!psivax!friesen@rand-unix.arpa