Penny Higgins - Storyteller • Artist • Scientist
Combining Science and Joyful Creativity
What’s it about?
The Heterostraci are armored jawless fishes that are a sister group (evolutionary offshoot, if you will) to the lineage that later led to fishes with jaws. This paper is a discussion of how the various species of fish tucked into the Heterostraci are actually related.Continue reading “Who Are the Heterostraci? – #UREES270 – 2018”
What’s it about?
The anaspids were a group of early, jawless fishes with bony armor covering their bodies. The authors discuss the structure of the bony armor and complete analyses to determine where anaspids actually fit into the evolutionary history of vertebrates.Continue reading “Anaspids, Jawless Fish Whose Armor Tell Us Where They Belong – #UREES270 – 2018”
What’s it about?
The Endangered Species Act exists to protect species from extinction. However, the means by which we define ‘species’ can affect what groups of organisms get this protection. The ‘textbook’ definition of species (populations of organisms that interbreed naturally and have living and fertile offspring) is what most people think of. This is known as the Biological Species Concept. But what about sub-species, or isolated populations of organisms (such as the Florida panther)?
Modern phylogenetics, including cladistics, allows species to be defined using molecular data and focuses more on dividing organisms into the smallest, distinct populations, which are likely to be reproductively isolated.Continue reading “How Definitions of Species Affect Conservation – #UREES270 – 2018”
What’s it about?
The authors observed the decay to two very similar organisms: amphioxus (Branchiostoma), a chordate, and the ammocoete larva (Lampetra), a vertebrate. It was observed that the distinctive characters that distinguish vertebrates from other chordates very quickly decay after death, resulting in both amphioxus and the ammocoete appearing to be merely stem chordates. Continue reading “Why Can’t We Tell If a Chordate Is a Vertebrate in the Fossil Record? – #365papers – 2018 – 35”
Minot, 1890, The Mesoderm and the Coelom of Vertebrates: The American Naturalist, v. 24, p. 877-898.
What’s it about?
At the start of every vertebrate’s life, they are merely a ball of cells. Then a hollow ball (blastula). Then a ball that’s been punched in on one side (gastrula) with a hole (blastopore). At the gastrula stage, the early embryo is composed of two simple layers. On the outside is the ectoderm (sometimes called entoderm), and on the inside is the endoderm.
A third layer, called the mesoderm, arises in vertebrates and later opens to form the body cavity or coelom (pronounced SEA-lome). The coelom is the open space in which our organs essentially hang. Our stomach, intestines, bladder, heart, lungs, liver, pancreas, etc. are not embedded in our body walls, but float and move relatively freely in the coelom, with some connections (mesentaries) to the body wall to keep everything from falling to the bottom. It’s this arrangement that makes things like laparoscopic surgery possible.
Anyway… At the gastrula ‘hollow ball of cells’ stage of an embryo, somehow mesoderm forms between the ectoderm and the endoderm, then divides to form the coelom and the lining thereof.
This paper looks at embryos of many different vertebrates, from sharks to mammals, to explore the origins of the mesoderm and the coelom.Continue reading “Making The Vertebrate Body Cavity – #365papers – 2018 – 33”
What’s it about?
The Jehol Biota is a group of fossils that preserve some of the best examples of feathered dinosaurs available. The fossils come from several localities in the Sihetun area of the Liaoning Province of China. The authors here used three cores collected around the region, plus some study of outcrops, to investigate the relative ages and environments of different parts of the Liaoning Basin.Continue reading “Assigning Age and Environment to Fossil-Bearing Cretaceous Rocks – #UREES270 – 2018”
What’s it about?
The “Tully Monster” (Tullimonstrum gregarium) is a fossil originally described from Carboniferous coal deposits near Mazon Creek, Illinois. It is also known from localities in western New York State, including Taughannock Falls near Ithaca. There has been a lot of discussion about what the Tully Monster is most closely related to (e.g. worms, arthropods, or vertebrates). In 2016, two papers were published that asserted that Tullimonstrum was a vertebrate. The authors here show why that interpretation is in error.Continue reading “Determining What the “Tully Monster” Really Is – #UREES270 – 2018″
What’s it about?
One thing that is truly unique among organisms is the concentration of sensory organs in the head of vertebrates. Ancestors of the vertebrates lacked this head. The authors discuss the embryological origins of the complex sensory systems of the vertebrate head.Continue reading “Getting A Head: What Makes Vertebrates So Special? – #UREES270 – 2018”
Instructor Assigned Paper 1 – Jan 19
What’s it about?
In order to have the science of vertebrate paleontology, we have to have the fossilization of bones. The authors use experimental methods to examine what happens early in the process of fossilization and understand the role of bacteria in the preservation of bone.Continue reading “The Beginning of Bone Fossilization – #UREES270 – 2018”
Friday Headlines, September 2, 2016
THE LATEST IN THE GEOSCIENCES
Today’s round-up:
Earth’s Oldest Fossils
First Stars Are Younger than We Thought
Little Bitty PterosaurContinue reading “Friday Headlines: September 2, 2016”
Penny Higgins - Storyteller • Artist • Scientist