Blog #332 Their Theropod Lineage Shows

Ophelia and her brood at sunset. 

This year’s nestlings have new names: the eldest nestling Rosie is 15 days old, followed  by Olan at 12 days and Lilibit at 10 days. I intended to name them after hawk-headed or  winged Egyptian gods (see Blog #326), but after friend Rose’s sudden death, I decided  to honor her passing and that of Olan a few years ago. Both tolerated my love of  Ospreys with knowing smiles. Their spirits now soar with the birds. Lilibit, the third and  youngest chick, was named for another friend, rather than Duchess Megan and Duke  Harry’s newborn.  

Ten day old Lilibit is still covered with the camouflaging striped gray and buff-colored  down. Olan is just moving into the Reptilian Phase, a transitional phase with many  changes. Rosie’s buff down is quickly being replaced with a dense, wooly, second  down, which will last another two weeks. Rosie is already in the Reptilian Phase with  his/her dark wooly down and oversized bluish-grey feet with long, black talons.  

In place of having teeth, Ospreys have a two-part stomach to digest their food. The first chamber is known as the crop where chemicals similar to  saliva, begin to break down the food. Once the food is coated in the 

chemicals it is moved to the second chamber called the Gizzard. Here the  food is "chewed." The gizzard contains sand and grain like particulars that  are used to help mash up the food. Rosie’s crop is becoming visible when full of  food. A conspicuous light tan streak runs down his/her back for added camouflage  against the background of the nest.  

Ophelia and her chicks, Rosie, panting, is in his/her reptilian best. 

At two weeks old, Rosie is the most mobile of the group and pushes aside his/her siblings to be first on line for feedings. (S)he routinely backs up to eject feces over the  rim of the nest. I’d like to say Rosie is adorable, but in truth s(he) is anything but. During  this transitional “Reptilian Phase,” the dark, scaly chick with prehistoric-looking deep  

Rosie, day 15, in his/her reptilian phase.

orange eyes, enormous beaks, and pin feathers sticking out all over, will crouch at  danger, suggestive of its ancient theropod lineage of the Cretaceous period, 65 million  years ago...and in Michael Crichton’s Jurassic Park. It’s clear that not all dinosaurs went  extinct at the end of the Cretaceous Period. One group survived, and we see their  descendants every day — birds. 

The extinction of non-avian dinosaurs at the end of the Cretaceous has long-intrigued  paleontologists. Discoveries have included shared skeletal features like hollow bones  and hips that allow walking upright, and fossils of feathers and nesting grounds. New  finds continue to fill in the bird family tree and shed light on ancient dinosaur behavior. 

One theory is that an asteroid impact 65 million years ago off the coast of Mexico  generated massive tsunamis, with impact debris cutting off sunlight for months, stopping  photosynthesis and causing freezing temperatures. Chemical reactions in the  atmosphere caused acid rain and long-term global warming, all of which extinguished  non-avian dinosaurs. However, at the same time, massive lava flows erupted across  what is now southwest India. The eruptions probably caused many of the same effects  as the asteroid impact. Although most scientists believe that the impact was the final  blow for non-avian dinosaurs, both events could well have played a role.  

Model of Bambiraptor, courtesy of SciNews. 

Most paleontologists have accepted the idea that birds are living dinosaurs for some  time. But the discovery of Bambiraptor has led to some intriguing new ideas about the  strong links between birds and dinosaurs. Bambiraptor was probably covered in  feathers and its skeleton was almost identical to that of a modern bird. Even though  Bambiraptor was only two feet long and weighing five pounds, it was a vicious,  raptor that hunted down and ate other dinosaurs.  

Bambiraptor belongs to the group of dinosaurs called dromaeosaurs, which are very  closely related to modern birds. Dromaeosaurs had both feathers and hollow bones  later used in flight, but first evolved in dinosaurs that lived on the ground or climbed  

trees. These dinosaurs could not fly because their arms were too short to function as  wings. Scientists now think that modern birds are very closely related to the family of dinosaurs known as dromaeosaurs, which includes Bambiraptor.

Roadrunner, courtesy of Chicago Zoological Society. 

Modern roadrunner’s anatomy is very similar to Bambiraptor: it has a S-shaped neck, a  pubis bone in the hip points backward, a V-shaped wishbone, folding arms, and three  primary toes on the feet. 

Eyes to the sky!  

Candace  

Candace E. Cornell  

Friends of Salt Point  

Cayuga Lake Osprey Network 

Lansing, NY  

cec222@gmail.com  

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