How To Make It Plural

Everyone has that small linguistic pet peeve. For some, it’s the differentiation between well and good. For others, it’s the improper use of apostrophes. For me, it’s improper plurals in scientific jargon.


When most English speakers need to make a word plural, the first instinct is to just add an ‘s’ to the end; if one is femur, then two must be femurs. Nope. Of all of these linguistic sins, in my experience this one is the most common. To make the word ‘femur’ plural, you add an ‘a’ instead of an ‘s’ (and tweak the spelling a bit); one is a femur and two are femora. Besides, femora is just more fun to say!


Let’s stick with the osteological focus. Again, for most people their first instinct is to turn ‘radius’ into ‘radiuses’ in order to make it plural. Instead, take off the ‘us’ and add an ‘i’; one is a radius, two are radii. Radii is one of my favorite plural words and it’s just so much fun to say!


And the last osteological term: scapula. And again, don’t add an ‘s’, just add an ‘e’. That probably seems counterintuitive but one is a scapula and two are scapulae.


Genus is a tough one. Some people default to trying to simply add an ‘s’ but others seem to know thats not right and try something else. Others don’t change the word at all in order to make it plural. I’ve heard many variations but the most common are ‘genuses’ and ‘genii’. Genus doesn’t act like the other words in this list; the plural form of ‘genus’ is ‘genera’. So that’s it.

Femur -> Femora, Radius -> Radii, Scapula -> Scapulae, Genus -> Genera.

And if this is confusing, just do what I do: use a different word! I tell my students that synonyms are for when you can’t spell or pronounce the word that you actually want to use. But really, don’t let this scare you. When in doubt, just power through and act confident even if you don’t feel it.

Word Wednesday: Australopithecus

Paleontology and paleoanthropology are full of unwieldy scientific names and these names crop up from time to time in news stories. I will be discussing the meaning of the names of three alliterative hominid species: Australopithecus afarensisAustralopithecus africanus, and Australopithecus anamensis.


Australopithecus breaks down into two parts: australo and –pithecusAustralo comes from the Latin word ‘australis‘ which means southern and pithecus comes from the Greek word ‘pithekos‘ which means ape. Australopithecus is a genus of gracile hominids that originated in eastern Africa around 4 million years ago and went extinct around 2 million years ago.


Anamensis breaks down into two parts: anam and –ensisAnam comes from the Turkana word for lake, and ensis is a Latin word which means belong to or originating in. Therefore, Australopithecus anamensis means southern ape originating in a lake. The first fossils were found  near Lake Turkana in Kenya and were named for the region. Fossils have also been found in the Middle Awash of Ethiopia. Australopithecus anamensis lived in East Africa between 4.2 to 3.9 million years ago.


Afarensis breaks down into two parts: afar and –ensisAfar is a region in Ethiopia and we already know that ensis means originating inAustralopithecus afarensis therefore means southern ape originating in the Afar. Many fossils have been found in East Africa and fossil sites include those in Hadar (part of the Afar region of Ethiopia) and Laetoli in Tanzania, as well as other sites in Ethiopia and Kenya. Australopithecus afarensis is best known for including Lucy and the makers of the Laetoli footprints. Australopithecus afarensis lived in East Africa between 3.85 and 2.95 million years ago. 

The Taung Child (By Guerin Nicolas via Wikimedia Commons)


Africanus is the Latin word for Africa, so Australopithecus africanus means southern ape from Africa. Unlike Australopithecus anamensis and Australopithecus afarensis, this species has been found at 4 sites in South Africa: Taung, Sterkfontein, Makapansgat, and Gladysvale. The first Australopithecus africanus fossil was the Taung Child found by Raymond Dart in 1924. The Taung Child was the first specimen to be included in the genus Australopithecus. They lived in South Africa between 3.3 and 2.1 million years ago.

This list only includes some of the gracile australopithecines. There are other species within Australopithecus, as well as the robust australopithecines that have been placed in either Australopithecus or Paranthropus. However, that is a discussion for another day.

To learn more about the species I mentioned above, I recommend the Smithsonian National Museum of Natural History’s Human Origins website. If you want to learn more about human evolution, I highly recommend John Hawks’ blog.

Check out this song about australopithecines!

Word Wednesday: Teeth

One of the key characteristics of mammals are their teeth. Unlike fish, reptiles and amphibians, mammals have different types of specialized teeth. This is why dinosaurs and sharks regrow their teeth, but humans only get two sets. There are four different types: incisors, canines, premolars, and molars.


Incisor comes from the Latin word ‘incisusmeaning cutting. These are your front teeth and, like the name suggests, they work like scissors to cut through food.


Canine comes from the Latin word ‘caninus‘ which means like a dog. Canines, or eye teeth, are longer, pointier teeth. They are used to hold food to tear it apart.


Molar comes from the Latin phrase ‘molaris dens‘ which means grinding tooth. Molars are your back teeth and are used to grind up food. Premolars are between your canines and your molars and are used in chewing to transition from the cutting of the incisors to the grinding of the molars.

Front view of the skull of Tasmanian Devil (Sarcophilus ursinus), showing Polyprotodont and carnivorous dentition. The modern accepted name is Sarcophilus harrisii. (Cambridge Natural History, Mammalia)

When studying teeth, scientists often use a dental formula. This is a simple way of showing the number of each type of tooth in one half of the jaw. To determine the total number of teeth, just double each part of the dental formula. For example, humans have four incisors, two canines, four premolars, and six molars in both the upper and lower jaws. That can be written either as (I2C1P2M3)/(I2C1P2M3) where the superscript numbers represent the upper jaw and the subscript numbers represent the lower jaw, or where the numbers on the top represent the upper jaw and the numbers on the bottom represent the lower jaw.

While humans have all four types of teeth and have the same number of teeth in our upper jaws as we do in our lower, that is not the case for all mammals. Cows have no upper incisors or canines, so their dental formula is . Dogs have more incisors than we do, as well as more premolars and fewer molars in their upper jaw than the lower: .

Despite there only being four different types of teeth, animals have greatly modified both their appearance and number. However, that is a topic for another day.

Word Wednesday: Mammal

One of the most common classes of animals are the mammals. It includes animals that many people know well: cats, dogs, bats, whales, etc. Most people have a pretty good idea of what constitutes a mammal.


Mammalia  comes from the Latin word ‘mamma‘ which means breast. Mammary glands, or milk producing glands, are one of the key features of mammals.

Besides mammary glands, all mammals also have hair, a single lower jaw bone (reptiles have 3 bones), 3 inner ear bones, cheek teeth with a divided root and an aortic arch (main artery in the heart) that bends to the left. Some traits are easier to observe than others and some of these traits aren’t as straightforward as they seem. For example, platypuses don’t have nipples like most mammals. Instead, they secrete milk through patches on their abdomen. Porcupines have modified hairs (quills) that they use to defend themselves from predators. And even whales and dolphins are some hair!

There are 3 types of living mammals: marsupials, monotremes, and placental mammals. Monotremes are the most primitive mammals and lay eggs. Today, the only monotremes–platypuses and echidnas–are found in Australia. Marsupials are slightly more derived than monotremes and give birth to underdeveloped young that mature inside a pouch. Modern marsupials live in Australia as well as South America and Eastern North America. Finally, placental mammals, including humans, are a relatively recent development. They give birth to live, relatively well-developed, young.

To learn more about mammals, check out the link below!

Linnaeus and the Breast

Taxonomic Hierarchy

Life is complex. In biology, scientists try to organize all of the living things on Earth through taxonomy. Taxonomy is a method of arranging these living things (taxis: arrangement, -nomia: method) and we have Linnaeus to thank for it.

Taxonomy is based on a hierarchy of classification; the lower you go in the hierarchy, the more closely related the living things are. These groups, from largest to smallest are Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. When I was in high school, I learned a mnemonic to remember the order of taxonomic classification: Did King Phillip Come Over For Good Spaghetti?

To make classification simpler, let’s choose two species and follow them through the hierarchy. Let’s compare the domesticated cat (Felis catus) and humans (Homo sapiens).

The largest layer of the classification hierarchy is Domain. There are 3 domains: Archaea, Bacteria, and Eukarya. Cats and humans are in Eukarya, so we’ll follow that path.

The next layer is Kingdom. There are 6 kingdoms: Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria. Cats and humans are in Animalia, so we’ll follow that path.

Classification hierarchy (via Wikimedia Commons)

Next is Phylum. The kingdom Animalia contains about 35 phyla. Cats and humans are in Chordata.

Next we have Class. The lower we go in the hierarchy the more and more choices we have. Cats and humans are in the class Mammalia.

Next is Order. Up until this point, humans and cats have fallen under the same classification. Cats are in the order Carnivora, while humans are in the order Primates. In plants, the suffix -ales denotes an order.

Next we have Family. Now the groups are getting much smaller. Cats are in the family Felidae, while humans are in the family Hominidae. The suffix -dae is used to denote a family within animals, while in plants -aceae serves the same function.

Genus is a commonly used level of classification. Cats are in the genus Felis, while humans are in the genus Homo.

Species is the most specific (pun intended) level of classification. When writing a species name, both the genus and species names are required. Cats are Felis catus and humans are Homo sapiens.

These aren’t the only levels of classification. Between levels there are superorders and suborders and tribes and subspecies and other small levels of subdivision. For example, humans are part of the tribe Homini. The use of these subdivisions is an exception, not a rule. Many species makes it all the way through the taxonomic hierarchy without using any subdivisions.

The most important thing to remember when it comes to taxonomy is that this system was entirely made up by humans to explain the world around us. We’re not perfect and sometimes things don’t fit neatly into these little boxes and the entire tree of life has to be redrawn. Regardless, taxonomy is a useful way for scientists to categorize and understand the world.

Word Wednesday: Stromatolite

Nearly every biology class that I have ever taken has mentioned stromatolites. They are an essential part of the history of the Earth and are an easy term to understand.


Stromatolite breaks down into two parts: stromato and -liteStromato comes from the Greek word ‘stroma‘ which means bed or mattress and lite comes from the Greek word ‘lithos‘ which means stone. In other words, stromatolites were mattresses of stone.

Stromatolites growing in Hamelin Pool Marine Nature Reserve, Shark Bay in Western Australia. (Wikimedia Commons)

Stromatolites were microorganisms that lived up to 3.5 billion years ago and are some of the oldest fossils. They are ‘laminated organo-sedimentary structures formed by the trapping and binding, and/or precipitation of minerals by microorganisms‘, specifically by cyanobacteria (blue-green algae). In other words, they are made of layers and layers of cemented cells. They were typically no more than half a meter tall, but in some places were as large as 5 meters tall! Cyanobacteria is thought to have contributed to the high level of oxygen in the the atmosphere by undergoing photosynthesis. You can find these ancient fossils in places such as the Black Hills of South Dakota and the Upper Peninsula of Michigan. Today, the best known modern stromatolites are found in Shark Bay in Western Australia.

To learn more about stromatolites, check out the links below!

UC-Berkeley: Fossil Record of the Cyanobacteria

Shark Bay

AMNH: A stromatolite from Mauritania

Word Wednesday: Harry Potter Spells

And now for something completely different. July 31st is Harry Potter’s birthday, so I thought that it would be fitting to discuss how the spells in the world of Harry Potter can break down as easily as any scientific term.


Lumos comes from the Latin word ‘lumen‘ which means light.  In the world of Harry Potter, Lumos is a basic spell that produces a beam of light from the caster’s wand.


Nox is a Latin word meaning night. It is the countercharm to Lumos and extinguishes the beam of light.


Incendio comes from the Latin word ‘incendium‘ which means ‘causing a fire’. It produces flames.


Locomotor is a Latin word meaning moving from a place. It is used in Harry Potter to move objects.


Obliviate comes from the Latin word ‘oblivio meaning being forgotten. It is used to make the subject forget an event.

Homenum  Revelio

Let’s take each of these words separately. Homenum comes from the Latin word homo‘ which means human and revelio comes from the Latin word ‘revelare‘ which means reveal. In the books, this spell is used to detect hiding people.


Expelliarmus needs to be broken down into expelli and -armusExpelli comes from the Latin word ‘expellere‘ which means to drive out and armus comes from the Latin word ‘arma‘ which means weapons. In Harry Potter it is used to disarm your opponent.

So there you go! All you really need to be a wizard is a knowledge of Latin and a vivid imagination.

Word Wednesday: Paleontology

I’ve talked a little about paleontology before, but I think it deserves a post of its own.


Paleontology breaks down into two parts: paleo and –ontologyPaleo comes from the Greek word palaio‘ which means ancient and ontology comes from the Latin word ‘ontologia‘ which means “metaphysical science or study of being”. Simply put, paleontology is the study of ancient life.

Paleontology is a broad and diverse field. There are vertebrate paleontologists who study ancient vertebrates, which can mean anything from the earliest fish to dinosaurs to mammoths. Then there are invertebrate paleontologists who study ancient invertebrates and paleobotanists who study ancient plants. After that, the fields get more complicated and interconnected: paleoecologists study the interactions of ancient communities, paleoclimatologists reconstruct the ancient climate, and paleoceanographers study the ancient oceans. Paleontology draws heavily from geology, biology and other physical sciences.

People frequently ask me “What’s the point of paleontology”. They don’t understand why we should study plants, animals and environments that might no longer exist today. And that’s just it: it’s important to understand the past. For a concrete example, consider global climate change. Global temperature and carbon dioxide levels have sky-rocketed in recent history. In human history, we have nothing to compare this to. That’s where paleontology comes in. During the Pliocene global temperatures and carbon dioxide levels were a little higher than today. Scientists can study those ancient plant and animal communities and use that information to predict a possible future trajectory for climate change. Simply put, the past is the key to the future.

Paleontologists and astronomers are surprisingly similar: we will probably never actually see what we study (until we go to Mars or clone a mammoth). In a sense, we’re time travelers. To be honest, sometimes learning about an ancient fossil site can feel like stepping back in time. By visiting places like The Mammoth Site and The Gray Fossil Site the average person can get an idea of what life was like millions of years ago. Just think, without paleontology we would have virtually no understanding of dinosaurs, the last Ice Age or where fossil fuels come from! There’s a reason why so many children want to be paleontologists: it appeals to a sense of curiosity and imagination.

Just for fun, here’s a song about paleontology by They Might Be Giants.

Word Wednesday: Brontosaurus

When I was a tour guide at the University of Michigan Museum of Natural History, I would ask the kids what their favorite dinosaur was and many of them would say Brontosaurus. It amazes me that even though scientists have known for 110 years that Brontosaurus was a mistake and never existed, it is still a strong part of American pop culture. Regardless, I think that Brontosaurus is one of the most epic dinosaur genus names.


Brontosaurus breaks down into two parts: bronto and saurusBronto comes from the Greek word ‘bronte‘ which means thunder and we already know that saurus comes from the Greek word ‘sauros‘ which means lizard. In other words, Brontosaurus literally means thunder lizard.

Here’s an abridged version of the Brontosaurus story. In 1877, Othniel C. Marsh discovered and described a new sauropod he called Apatosaurus. In 1879, he found another, more complete skeleton and named it Brontosaurus. Brontosaurus became well known and replicas went up in museums across the country. In 1903, Elmer Riggs examined the specimens and concluded that there were not enough differences to justify two different genera and since Apatosaurus came first, there was no need for the name Brontosaurus. Marsh’s specimens weren’t associated with skulls, so he chose one that he found nearby. It wasn’t until 1979 that scientists realized that he had picked the wrong one. Regardless, most people are still infatuated with Brontosaurus despite knowing that it never existed.

The moral of the story is that science is ever changing and we are constantly adjusting our view of the world to reflect the most up-to-date research. Whatever your attachment to Brontosaurus, just remember: dinosaurs aren’t really gone. They persist today as birds, and doesn’t that make the world seem more weird and wonderful?

If you can’t get enough of Brontosaurus and want to learn more about the confusion, check out the links below!

NPR’s explanation of the Brontosaurus confusion.

Check out this interview with Brian Switek, author of My Beloved Brontosaurus, about dinosaur misconceptions.

Here’s a nice summary of the importance of My Beloved Brontosaurus.

Hank Green hosted a Mental Floss video about 50 Science Misconceptions.

xkcd has an amusing take on Brontosaurus’ history.

Word Wednesday: Ratite

After weeks of learning about fossils and geologic time, let’s talk about something that’s still alive: ratites.


Ratite comes from the Latin word ‘ratis‘ which means raft. Ratites are large, flightless birds. The name ‘ratite‘ refers to the the large, flat sternum of these birds that lacks a keel. Today, there are five orders of ratites and more than 10 different species.

Male ostrich in Ngorongoro (from Wikimedia Commons)

Ostriches (Struthio camelus) are the world’s largest and fastest birds. They can grow to over 2.5 meters tall and weigh over 100 kilgrams. They live across much of Africa and prefer open savannas and deserts. Ostriches are the only ratites with a native range north of of the Equator.

Greater Rhea (from Wikimedia Commons)

There are two species of ratite native to South America: the Greater Rhea (Rhea americana) and Darwin’s Rhea (Rhea pennata). The Greater Rhea lives in the open grasslands of southeastern South America, while Darwin’s Rhea lives in Patagonia and the Altiplano of southern and western South America. In 2000, three pairs of rheas escaped from a farm in Germany and have managed to maintain a population. In 2008 this group was estimated at around 100 birds.

Northern Cassowary (from Wikimedia Commons)

The island of New Guinea is native to three species of ratite: the Northern Cassowary (Casuarius unappendiculatus), the Southern Cassowary (Casuarius casuarius) and the Dwarf Cassowary (Casuarius bennetti). Cassowaries live in forests and the range of the Southern Cassowary extends all the way to the northeastern tip of Australia. These species have evolved dagger-like claws on their inner toes and all three are suffering from habitat loss.

Emu (from Wikimedia Commons)

Australia is native to the Emu (Dromaius novaehollandiae). They are the world’s second tallest bird, after the ostrich. The emu is the only bird to have gastrocnemius muscles in their legs (the equivalent of the calf muscles in humans). They live throughout Australia and, like the cassowary, have sharp claws on their toes. The emu, with the red kangaroo, is part of the coat of arms of Australia.

North Island Brown Kiwi (from Wikimedia Commons)

The islands of New Zealand are native to five species of ratite: the Great Spotted Kiwi (Apteryx haastii), the Little Spotted Kiwi (Apteryx owenii), the Okarito Kiwi (Apteryx rowi), the Southern Brown Kiwi (Apteryx australis) and the North Island Brown Kiwi (Apteryx mantelli). Kiwis are about the size of a chicken, making them the smallest of the ratites and they lay the largest egg in relation to their body size of any bird. All of these species are suffering the ill effects of habitat destruction (the Okarito Kiwi is critically endangered and the North Island Brown Kiwi is endangered). Kiwis are a national symbol of New Zealand: it is the nickname for New Zealanders and appears on the coat of arms for the country as well as stamps and badges.