RANDOM THOUGHTS #290

Steve Cole ponders thoughts on dinosaurs:
       

1. Tyrannosaurus-Rex specimens found lately:
Black Beauty (Alberta, 1980 ­ 28 %)
Stan (South Dakota, 1987 ­ 63 %)
Wankel Rex (Montana, 1988 ­ 46 %)
Sue (South Dakota, 1990 ­ 85 %)
Scotty (Saskatchewan, 1991 ­ over 70 %?)
Samson (South Dakota, 1992 ­ over 70 %?)
Peck¹s Rex (Montana, 1997 ­ 40-80 %?)
Bucky (South Dakota, 1998 ­ 34 %)
B-Rex (Montana, 2000 ­ 37 %)
Jane (Montana, 2001 ­ 50 %)
Tristan (Montana, 2010 ­ 57 %)
Trix (Montana, 2013 ­ 80 %)
Baby Bob (Montana, 2013 ­ over 50 %?)
Tufts-Love Rex (Montana, 2016 - ???)

Note that different scientists have different ways of calculating percentage (number of bones, weight of bones, volume of bones) so the numbers aren't necessarily comparable.
     

2. Dinosaurs have long been divided into two groups, the bird-hipped ones (stegosaurus, triceratops, duckbills, but not birds) and the lizard-hipped ones (all of the meat eaters and all of the sauropods like Brontosaurus). A recent study suggests that the theropods (meat eaters) are more closely related to the bird-hipped ones than the sauropods. The issue is hotly debated.
        

3. During the latest Cretaceous, the land masses had separated and the dinosaur populations of the northern and southern hemispheres were very different. Tyrannosaurids, duck bills, and horn-faces dominated western North America and Asia. Abelisaurids (a meat eater, including Carnotaurus) and titanosaurids (bronto-critters) dominated in South America, India, and Madagascar. Europe was a bunch of islands with smaller species. Eastern North America was another continent with a separate population.
    

4. Trackways (solid stone that was once mud with dinosaur footprints in it) are one way we learn about dinosaurs, but they are far less accurate than one might assume. The dinosaur might have had mud-caked feet. The tracks might have been eroded before they were covered up. The pressure of covering them up might have flattened and expanded the tracks. Nobody knows just how muddy the ground that became the track way was, or how fast the dinosaur was running. Exposed trackways are subject to erosion, often over many years before humans find and preserve them. Trackways are also favorite targets of thieves and illegal collectors who sell the cut-away stone blocks to millionaires with secret illegal collections.
   

5. The latest analyses indicate the crocodiles and turtles are more closely related to each other than either is to lizards or dinosaurs.
       

6. While not dinosaurs (actually, long after them), the Pleistocene carnivores Dire Wolf and Saber-Tooth Tiger are modern favorites and are often found in bags of plastic dinosaur toys. They had two very different hunting strategies. Dire wolves, like modern wolves, chased down and wore out their prey, while saber-tooth tigers were ambush hunters (leaping cats, like all modern cat species other than cheetahs). This was determined by analysis of broken-bone injuries found amount hundreds of skeletons.
       

7. Zhongjianosaurus is a new dinosaur from China, and the smallest carnivore yet found. It was smaller than a pigeon, but was clearly a dinosaur (a micro-raptor) not a bird or bird ancestor. (Micro-raptors and bird ancestors are from the same branch of the family tree.)
  

8. It is hard to tell from a few loose bones or teeth just what kind of animal you have found. Police who find random bones today can do DNA tests to find out that their crime scene is actually just the place where somebody bar-b-qued some pork ribs. No such luck with dinosaurs. Bushels of dinosaur teeth turned out to belong to phytosaurs (alligators), a huge pterodactyl wing bone turned out to be a tree trunk, and most scientists think that protoavis (claimed to be the earliest bird, dozens of millions of years before any other) is a jumble of bones from at least two and possibly four unrelated animals that were all swept downstream in a flood and buried in a eddy.
      

9. The ICZN (International Committee for Zoological Nomenclature) keeps track of every animal name ever printed. In one recent case, someone named a new dinosaur only to find out that the name had already been used. In another case, a name given to a new dinosaur had already been used for a modern-day beetle. Once a name is used (even if the name proves to be invalid) it cannot ever be used again. Sometimes different scientists find different parts of the same kind of animal and each gives it a name; this is why the Brontosaurus I grew up with suddenly changed when it was found that a few random bones given the name Apatosaurus were in fact part of a Brontosaurus. The same scientist named both and while he always suspected they were from the same critter, he always preferred Brontosaurus but ICZN rules insist on Apatosaurus. Later, more skeletons were dug up and some started to argue that Apatosaurus and Brontosaurus were in fact related animals like a horse and a zebra. [I was told once that actors unions have a similar rule so that there can never be two actors of the same name. This often causes problems when a model or singer tries to break into acting only to find out that the name they have built up over a decade was used by some two-bit actor 60 years ago that nobody remembers. I¹m just saying.]

        

10. Reptiles cannot chew bones; they can only swallow them whole. Theropod (meat-eating) dinosaurs, on the other hand, easily chewed up the bones of smaller (and sometimes larger) animals and ate them. (We know this because of bone fragments found in fossils of dinosaur poop.)  They did this with incredible bite forces (T-rex reached 8,526­34,522 newtons), teeth that worked more like scissors than molars, and biting repeatedly in the same place to shatter the bones into fragments.