The gang discusses two papers that study the paleoecology of the Ediacaran fauna. The first paper looks at environmental information that can be gleaned from the microbial mats these organisms lived on, and the second paper studies how different Ediacaran fossils are distributed on this microbial mat. Meanwhile, James is having a week, Curt is unsure about chips, and Amanda is comfortable being very on brand.

Up-Goer Five (Curt Edition):

The friends look at two papers that study some very old animals that lived a long long time ago and lived on these beds of tiny tiny tiny animals and not animals. In fact, these two papers are also interested in the beds these things lived on and how they lived on the bed. The first paper looks at these parts of the beds and how you can find them in different beds made of tiny tiny tiny animals and not animals. There are these lines in the beds that are found in some beds but not all of the beds. They think that the way water moves over the beds may cause these lines to form. The other cool thing they find is that the animals are found when there are these lines, and are not found when there are not these lines. This means that the way the water moves might be important for these animals to live.

The second paper looks at how these animals lived in space with each other. Did they want to live close to each other or did they want to be far from each other, or do they not really care? Some earlier papers had said they wanted to be far from each other, which is weird when we look at animals in the big blue wet thing today which want to stay close to each other. So they run a lot of studies on three different animals that can show if they are close to each other because they all need the same thing (and that thing is in small parts around the ground) or if they seem to want to be very close to each other because they either use each other or they can not move far from each other. They show that these animals all show that they are close to each other, but two of the animals are close because they all want something that is in just a few places. One animal shows a really strong need to be close, which could mean that this is something about the animal that makes new babies be closer to the father/mother. This shows we can learn things about how these animals lived and why they lived where they did, even for things that are very very very old.

References:

Boan, Phillip C., et al. "Spatial  distributions of Tribrachidium, Rugoconites, and Obamus from the  Ediacara Member (Rawnsley Quartzite), South Australia." Paleobiology (2023): 1-20.

Tarhan, Lidya G., Mary L. Droser, and  James G. Gehling. "Picking out the warp and weft of the Ediacaran  seafloor: Paleoenvironment and paleoecology of an Ediacara textured  organic surface." Precambrian Research 369 (2022): 106539.

The gang discusses two papers about inferring life habit and ecology from extinct animals. The first paper summarizes the data for ichthyosaur birth to see if they really do preferentially come out tail first, and the second paper investigates a fossil that could complicate the narrative for the origins of a European sabretooth cat group. Meanwhile, James has opinions about browsers, Amanda is camouflaged, Curt needs a drink, and everyone is surprised by a paper for the first time in a long time.

Up-Goer Five (Curt Edition):

The friends talk about two papers that looks at how animals did things and where they lived in the past. The first paper looks at a group of animals that lived in the water and had their kids inside them. This group used to be on land before they went into the water for all time. Lots of people say that when a group of animals goes from being on land to being on water, they need to change the way the babies come out of them, with the head coming out last so that they do not breathe in water. This paper looks into this to see if this is true. It turns out that lots of things today that used to be on land but are now in the water and have kids inside them usually have the kids come out with the head last. However, this is not always what happens. And, when the kids come out head first it is fine and they do not die and the mom also does not die. When we look at the parts of the dead animals from a long time ago that live in the water, we also see that, even in the groups that everyone says they go out head second, there are some that show they come out head first. It seems like, instead of being a change that is always true, these animals went from being most of the time head first, to being half and half head first, to being most of the time head second but sometimes head first.

The second paper looks at a group of angry animals with hair and long teeth. This group is found all over the world in the past and this paper is looking at one group that is most of the time found in one place but may have also had some groups close to it from other places. This paper names a new type of these animals and says that it is the first of this group, but also the study they do says that it isn't so that is weird. They also do another study to show that this group went through most of its big changes in this new place, but the study they do also seems to say that it is a third different place where a lot of important things happen but they do not talk about it. This paper is weird.

References:

Jiangzuo, Qigao, et al. "Origin of  adaptations to open environments and social behaviour in sabretoothed  cats from the northeastern border of the Tibetan Plateau." Proceedings of the Royal Society B 290.1997 (2023): 20230019.

Miedema, Feiko, et al. "Heads or tails  first? Evolution of fetal orientation in ichthyosaurs, with a scrutiny  of the prevailing hypothesis." BMC Ecology and Evolution 23.1 (2023): 1-13.