Hans-Dieter Sues

The last four decades have witnessed a revolution in the study of dinosaurs. Scientists no longer examine just the structure of the skeletons and the relationships of these fascinating animals, but have started probing issues of their biology. How did dinosaurs move? How did they feed? What was their circulatory system like? How did they…

Changing Planet

The middle ear of mammals contains a chain of three tiny bones (auditory ossicles), the hammer (malleus), anvil (incus), and stirrup (stapes). This chain transmits and amplifies sound vibrations from the eardrum to the inner ear. The eardrum (tympanic membrane) itself is stretched across an additional bone, the ecto­tympanic. In all other land vertebrates, a…

Wildlife

The giant extinct invertebrate Arthropleura resembled some modern millipedes, but could grow to be more than one-and-a-half feet wide, and may sometimes have been more than six feet long. Reconstruction of the giant millipede Arthropleura from the Pennsylvanian and earliest Permian of North America and Europe. The head capsule (marked by an asterisk) is shown…

Changing Planet

,

A new study of venomous reptile fossils sheds light on the evolution of snake fangs. By Hans-Dieter Sues Venom is a highly effective means to subdue and kill prey before eating it, as well as a great defense against predators. Furthermore, studies have shown that some snake toxins can also help in breaking down proteins…

Changing Planet

,

By Hans-Dieter Sues Charles Darwin noted that the oldest fossils known in his day already represented quite complex life forms such as trilobites, an immensely diverse group of extinct marine arthropods most closely related to horseshoe crabs, spiders, and their relatives. We now date these remains as middle Early Cambrian in age. Because Darwin assumed…

Changing Planet

,

By Hans-Dieter Sues The oldest known birds, classified in the genus Archaeopteryx, lived near the end of the Jurassic Period (145.5 to 150.8 million years ago).  Although Archaeopteryx has a fully developed plumage its skeleton still retains many features of its dinosaurian precursors, one of which is jaws with teeth. With the exception of some…

Changing Planet

,

By Hans-Dieter Sues About 60 million years ago, a group of extinct ground-dwelling birds of often spectacular size and with proportionately enormous heads, the Phorusrhacidae, first appeared in South America, an island continent until about three million years ago. They are informally and memorably known as “terror birds.” One species, Titanis walleri, crossed into North…

Changing Planet

,

A remarkable new discovery redates the evolutionary split between the Old World monkeys and the ape-human lineage. By Hans-Dieter Sues The higher primates of the Old World (Catarrhini) are divided into two major lineages, one comprising the living monkeys of Africa, Asia, and Europe and their fossil relatives (Cercopithecoidea), and the other, humans, great apes,…

Changing Planet

,

By Hans-Dieter Sues Among the great mammalian predators from the Pleistocene Epoch (1.8 million to 10,000 years ago) of North America, an enormous cat stands out. Only the giant bear Arctodus simus (discussed in a previous blog) exceeded it in size. No, I am not talking about the famous saber-toothed cat, Smilodon fatalis. Renowned American…

Wildlife

,

By Hans-Dieter Sues In the movie The Lost World (1997), the eccentric chaos theoretician Dr. Ian Malcolm (Jeff Goldblum) remarked on the all-too-soon apparent instability of the “Jurassic Park” world: “Life will find a way.” It always does. Some animals and plants make a living in almost unimaginably weird ways. For an evolutionary biologist like…

Wildlife

,