STL Science Center

STL Science Center

11 June 2020

An Exciting Opportunity

From the Facebook page of Julius Csotonyi:

A twist! On Sunday, join me in a drawing lesson on a rare modern-day survivor of the last ice age: the arctic ground squirrel or ᓯᒃᓯᒃ (pronounced "siksik") (Urocitellus parryii). Yukon paleontologist Dr. Grant Zazula will provide scientific commentary on this interesting (and large!) species of ground squirrel while I demonstrate its illustration, in an online event hosted by the Yukon Beringia Interpretive Centre at 1 pm Pacific Time on Sunday, June 14.

04 June 2020

Penguins Part II

Inkayacu, was approximately the same size as Palaeeudyptes

Fossil penguins were not always penguin "shaped", as we saw with Waimanu, but they became more distinctively penguin-like over time, as we saw with Kumimanu. Intermediate family members like Perudyptes and Anthropornis continue this "penguinification" trend of the overall body plan throughout the Eocene era and, by the times of Icadyptes, Palaeeudyptes, and Inkayacu, penguins look like the animals we think of when we hear the name penguin. There is one rather enormous exception to their recognizable penguin form: these are very tall penguins. Additionally, some of these penguins were likely still using their feet, in some capacity, in propulsion for swimming. Though we mentioned that it appeared as though Kumimanu may not be using its feet anymore to swim, it has been noted that the feet and ankles of some of these larger penguins indicate that they may have still played a role in swimming.The Eocene was an age of giant birds. Whereas the "Terror Birds" ruled portions of South America terrestrially, the giant penguins were taking to the ocean and at least terrorizing fish populations. Sharks were still apex predators in the ocean. Whales were in the process of fully transitioning from land to water. Enormous penguins could have been filling a niche that is now occupied by small whales and dolphins (and even smaller sharks like the reef sharks). Whatever their absolutely exact role, they were clearly highly successful birds that transitioned back from a terrestrial lifestyle to a nearly fully aquatic lifestyle. They did so as large animals that, over time, became increasingly efficient swimmers with streamlined bodies. Even if whales, dolphins, and smaller sharks (possibly seals and sea lions as well) pushed them into a finer definition of a niche, one which they currently occupy as pursuit predators. The nuances of penguin evolution, locomotion, diet, and the life histories of individual species are all complex topics that span the careers of scientists. Hopefully these two discussions are helpful in a very general sense to understanding penguins and their history.

01 June 2020

Penguins Part I

Waimanu manneringi ©Nobu Tamura
We know a lot about fossil penguins. Partly, this is because we have a fairly large number of fossils from penguins, which is a rarity for birds as a group in general. It's also a bit of a blessing. There are a number that are a little more well-known for various reasons (mostly to do with publication and news cycles) like Waimanu, Inkayacu, and Perudyptes; all penguins described since 2006. However, we have been recovering and describing penguin fossils since much earlier times: Pachydyptes (Oliver, 1930), Paraptenodytes (Ameghino, 1891), and Palaeosphenicus (Morino and Mercerat, 1891) are notable examples. Not all penguins are the same, so lumping them together is not really fair. However, their overall body plans are fairly conservative. Most members of the penguin family are recognizably penguin-like though ancestral members of the family are not exceptionally penguin-like. This includes Waimanu, an early member of the penguin family that has some penguin-like traits, but looks less like a penguin than we would imagine even an early penguin might appear. Waimanu has a longer tail and more wing-like upper limbs than we would expect a penguin to possess. However, its bill does look very much like the bill that we associate with fish catching birds and is reminiscent of that we see in penguins. The legs of Waimanu are more like those of a loon or a grebe and do not appear to be very useful for walking on land (just like those of loons and grebes). The position of the legs are better for swimming than for walking, to be honest, and from what we know about penguins, this makes a lot of sense.

Kumimanu biceae ©Nobu Tamura
Penguins do not swim with their legs though, they swim with their fins, their wings, providing propulsion underwater. So how does a penguin transition from leg power to wing power? The next oldest penguin we know (currently) from fossils, Kumimanu is decidedly more penguin-like. The feet look more like penguin feet. The tail is shorter than Waimanu's tail. The bill is still rather large and fish catching; not entirely penguin-like yet. We do have more flipper-like wings with Kumimanu, likely indicating that the legs are no longer propulsive and the flippers have taken over this function. The wings are not entirely like flippers that we see in modern day penguins though. Also, as we can see in Nobu Tamura's illustration, Kumimanu was a rather large early penguin. There are larger penguins that we know of, but rather than attempting to discuss all of the very important penguin fossils in one post, we will continue tomorrow with other notable penguins, some of which may be the largest penguins that ever lived.