April 2003
Ant Breathing Study by Field Researcher
Mark Westneat (Field Museum Zoology) was lead author on a cover article in Science reporting that x-ray studies done at Argonne show that ants and beetles actually do respire like us lunged creatures. It has been known that insects breathe through a system of tubes called tracheae that connect via spiracles that open and close. Both passive diffusion and physical activity were believed to explain how the gas dispersed within the bodies. There was up to a 50% volume change in the major tracheae of the thorax and head in the 3 species studied (ant, beetle and cricket). In addition they observed 3 other activities going on including abdominal pumping, autoventilation, and circulatory fluid motion, but these could not account for the tracheal activity. With the spiracles closed this compression would help diffuse the gases into the tissues. This compression may be driven by the contraction of jaw or limb muscles, which is common among animals.
Wings May Come & Go in Insects
In a Nature article by Whiting et al the evolution of insect wings in stick insects is studied. Wings allowed insects to avoid predators, find new food sources and find new homes. Over the course of time many insects have become flightless but no return to wings had been found to date. It had been thought that once something as complicated as wings disappeared, it would not reappear. This would be because mutations in parts of the process could make the wing-making process impossible again. He studied the DNA of 37 species and made a tree, which at first appeared to be upside down. The most base 16 species had winglessness and at the top wings reevolved four times after a 50 MY rest. Today there are species with wings, without wings and with partial wings. Some are questioning this report and wonder if the wingless ones might have had some remnants just like blind cavefish still have precursors of eyes.
New Ankylosaur from China – Crichtonsaurus
Dong et al report on the finding of a new Late Cretaceous ankylosaur from Liaoning (where else?) China and named it Crichtonsaurus bohlini. They have a partial left mandible with 3 teeth, several vertebrae, shoulder girdle, some leg bones and several scutes and plates. They estimate that it was about 3 meters long based on the vertebrae. They named it after the author of Jurassic Park – Michael Crichton and a Swedish vertebrate fossil collector, Dr. Bohlin.
New Therizinosaur Reported from Mongolia - Erliansaurus
This dinosaur was listed among last year’s new dinosaurs, but the article has just come out with more information. The article by XU, Sereno et al names the new therizinosaur for the site area of Erlian and for the beautiful hand of the fossil – Erliansaurus bellamanus. It is Upper Cretaceous and the holotype includes 5 vertebrae, left forelimb (less the carpus), partial right illium and pelvis, and part of the right leg. It is a small therizinosaur but may not be a full adult yet based on the weak suture on one of the vertebra. It is believed to be between primitive (Beipiaosaurus) and derived therizinosaurs and indicate that these animals may have been more diverse and more common than previously thought.
Writer of Shortest Short Dinosaur Story Dies
Guatemalan short story writer Augusto Monterroso has died at the age of 81. “El Dinosaurio” or “The Dinosaur” reads as follows
“When he awoke, the dinosaur was still there.”
I will try to find copies of it for those of you interested in reading it (ha-ha).
Flynn & Goodman Nature Article on Madagascar Carnivores
Theories to explain the presence of the four orders of terrestrial mammals in Madagascar call for up to four colonizations for the carnivora alone since the island was separated from Africa and India over 88 MYA (the physical separation from Africa started 165 MYA and from India 88 MYA). The four orders there today include carnivorans, primates, rodents and lipotyphian insectivores that are all placental mammals. Their history is hard to find because the Tertiary fossil record is very poor. This study used a multigene analysis to determine a single colonization for carnivores to Madagascar by an African ancestor. The major methods of population include Gondwanan vicariance meaning they all have ancient divergence dates, a landbridge from 45 to 26 MYA, and the sweepstakes dispersal model with random dispersal dates for groups that could withstand over water dispersal. The gene analysis showed colonization between 24 and 18 MYA (outside the Gondwanan vicariance and landbridge theories) favoring the sweepstakes theory. They also looked at lemurs and found a date of 66 to 62 MYA indicating the sweepstakes theory and negating any thoughts that carnivores and lemurs rafted over together. This kind of genetic data helps to answer questions when the fossil information is scant. This article in Nature was authored by Yoder and Goodman of the Zoology department at The Field and by Flynn and Zehr in Geology (with 3 others).
Longest Nautiloid Found in Arkansas
Three undergrads from the University of Arkansas have found a 325 MY old fossil that is 8 feet long. This is the longest actinoceratoid nautiloid in the world. The previous record holder is a 7 foot 2 inch (about 2.5 meters) one found near there in 1963. It is identified as belonging to the extinct species Rayonnoceras solidiforme that lived in a shallow sea. The geology professor of the discoverers, Walter Manger, feels that this specimen confirms his theory that this is a pathological giant. He believes that they would have lived like modern squid, mating, laying eggs and dying within a 3 or 4 year lifetime. However, these giant animals would have been made sterile by parasitic trematodes and lived for decades since their energy was not used up with reproduction. Now there are 2 specimens that support this. They believe that they have the whole shell with the last living chamber and it is in pretty good shape. In addition they may know the sex if the fossil animals were like their modern relatives. In modern nautiloids the females have a wider aperture. If this holds true then they have just found a female, because the aperture of the 1963 fossil is a third as wide as this new one.
Lanzendorf Dino Art Collection Sold!
Yes it’s true and it is not going to The Field. It was bought by the Children’s Museum of Indianapolis that will display it in the whole third floor of its new Dinosphere museum set to open in 2004. And I hear that John is now collecting Asian art so an era has ended. Sad.
Earliest T. rex Fossil Identified
A tooth was found in the collection of the Peabody Museum that had been collected in 1874 and put into a drawer. The first T. rex was found in 1902 and named in 1905 so this fossil predates that. Ken Carpenter from Denver studied the tooth in the Yale collection and announced his discovery of the earliest T. rex fossil ever found. It had been found by Edward Berthoud a collector working for Marsh. It is about 3.5 inches long and about 1.5 inches wide and was filed with miscellaneous teeth.
Scientific American Feather Story
The interesting thing about the Scientific American cover article entitled “Which Came First, the Feather or the Bird?” is that it is by two leading bird authorities, Richard Prum and Alan Brush (not by dino experts) and is subtitled “A long cherished view of how and why feathers evolved has now been overturned.” This article proposes an alternate theory to the ‘scales to feathers theory’ that has been common until now. They have developed a 5 stage process showing its origin as a hollow cylinder with a follicular collar produced by the epidermis (Stage 1). A tuft of barbs is formed from the calamus in Stage 2. Stage 3 has two possible paths, one is a planar feather with simple barbs and a central rachis, and the other with barbs and barbules attached to the base, ultimately arriving at a planar feather with branched barbs and open vane. This step in the process is not clear at this time. In Stage 4 the barbules hook together to form a closed pennaceous vane and in the final Stage 5 we see the asymmetrical flight feathers developing. All these steps have been backed up with DNA data that studied two important pattern genes (the sonic hedgehog or Shh and the bone morphogenetic protein Bmp2). These genes are known to play a role in growth of limbs, digits, hair, teeth and nails. So what are birds? They are one of the group of feather bearing dinosaurs that evolved the ability to fly using specialized feathers. Feathers were “exapted” for flight after substantial development and complexity. There are many possible reasons for the origin of the feather that we still do not know. It is wonderful to see this theory come from bird men.
Karen Nordquist, ESCONI Paleontology Study Group
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