One of these skulls is not like the others

When we receive queries for identification of skulls or specimens, we turn to our large specimen collection to find those that look similar and may help in the identification process. Among other osteological features we can look at the proportions of the skull, along with the size, number and spacing of the teeth. All these features of a recently received picture of a specimen in question led me to suspect that the specimen is foreign to the Great Lakes, and based on the very small size of the specimen I suspected that it may be a Round Goby. Following I will show you some of the specimens I looked at to bolster my conclusion.

Let’s start with a picture of a Round Goby from our collection:

skull of OSUM104702 Neogobius melanostomus Round Goby

OSUM104702 Neogobius melanostomus, Round Goby

Note the width of the skull, and the abundance and spacing of the teeth on this specimen.

The species that I considered to have the skull that would most closely match the proportions of the putative goby skull was the Central Mottled Sculpin.

head of OSUM37269 Cottus bairdii Mottled Sculpin

OSUM37269 Cottus bairdii, Mottled Sculpin








But here you can see that the head of the Mottled Sculpin is actually wider than, and the teeth proportionally not as large as those of the Round Goby (there are several other skeletal differences but those sufficed for this diagnosis).

There are several native fish that are carnivorous and have caniniform or cardiform (small, numerous and closely spaced) teeth that I mused over, but as you can see almost all of those have much narrower skulls and/or have shorter, fewer and more widely spaced teeth than the skull in question.

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Note: The Sauger, very close in appearance to the Walleye, was once abundant in Lake Erie but is now caught very seldom in the lake and its tributaries.

As you can see there is nothing quite like the Round Goby among our native species, and we should no doubt be thankful for that!

head of OSUM104702 Neogobius melanostomus Round Goby

OSUM104702 Neogobius melanostomus, Round Goby

Let us hope that the situation remains the same, and in the meantime, if you find a good use for these little monsters feel free to apply it and let us know your ideas.


About the Author: Marc Kibbey is Associate Curator of the Fish Division at the Museum of Biological Diversity.


What it takes to be a successful Invader

Invasive species have received a lot of bad press, but let’s face it, some of these alien species really have what it takes to make it!  One example of a highly successful invasive species is the Round Goby, a native to central Eurasia including the Black Sea and the Caspian Sea.

Male Round Goby in black spawning coloration

Male Round Goby in black spawning coloration

Identifying an alien

Recently a graduate student in Michigan sent a request for identification of a fish skull.  When I saw the skull on a photo that the student attached to the inquiry my first thought was that this is a species I haven’t seen before.  I was thinking to myself, “in my mind I’ve got a fairly good catalog of all the native species that are found in the Great Lakes, so this one is probably exotic”.  Furthermore, I examined the teeth and the rest of the skull picture, and found features that are similar to the marine blennies and gobies that I’m familiar with; quite possibly a Round Goby.

OSUM 104701, Neogobius melanostomus skull

OSUM 104701, Neogobius melanostomus skull

When one observes the teeth of a Round Goby skull, it becomes readily apparent that they are eminently suited to catching prey: numerous, closely packed and somewhat curved teeth. Once the fangs are sunk into the prey’s body it would be difficult to wriggle out of the goby’s maw.  Speaking of the “maw”, the width of the Round Goby’s head and mouth are somewhat disproportionately large in comparison to the size of the body.  This aspect of the anatomy amplifies the capacity of the fish to suck in its prey.  By opening the mouth quickly a vacuum is created, which when combined with the sudden forward lunge that the goby employs toward the prey, improves the likelihood of successful capture.

Neogobius melanostomus are extremely aggressive and will challenge fishes larger than themselves, outcompeting native fish for preferred habitat as well as preying on other fish’s eggs and young.

What makes the Round Goby so successful?

Round Gobies are found primarily in the benthic zone of the water body, from the bottom of shallow areas down to 70 feet in depth.  They prefer areas where there is plenty of cover such as around rocks, sticks and logs.  The species has been found to tolerate polluted conditions, which enables it to occupy areas that less tolerant species cannot live in. This increases their opportunities to grow into a large population that aids in overcoming the other species in less polluted areas.  Another aspect of their biology that enhances their prowess is a highly developed lateralis system, a fishes’ sensory system conveying environmental information to the brain and making them an effective competitor and predator in dark, murky conditions as well as in clear daylight.

High productivity is a hallmark of an effective invader.  A mature Round Goby female is able to produce over 3,000 eggs, the older the female the more eggs they produce.  The male uses posturing and coloration (see the photo above) to attract females to its nest, often mating with more than one female.  The females spawn up to six times in a season, which lasts all summer long from April through September. Let’s do the math: a female could produce 18,000 young in just one year, that’s a lot of Round Gobies!

Although the deleterious effects of this intruder are considerable in scope, as some research here at OSU has shown, one must nonetheless admire their capabilities.  But we should keep in mind that without our assistance it is doubtful that Round Gobies would have spread so far and certainly not so quickly.  Their ability to tolerate euryhaline conditions, a wide range of salinities, facilitates their natural spread under normal conditions over a much longer time. It has allowed them to survive in the ballast waters of vessels and occupy new areas when the ballast is flushed.

Although they are best known from the Great Lakes they are now found in the lower reaches of larger rivers and have been captured in the Illinois River drainage, presaging their invasion of other Mississippi River tributaries.

map of Round Goby invasion in Great lakes regionBut thus far the most dramatic spread of the Round Goby has occurred in the Great Lakes of North America where a lack of effective competitors facilitated their occupation of new territories.

Northern Europe, too, has suffered from a Round Goby Invasion as shown in these maps and the potential for their spread in Europe is estimated to be much greater. You can follow them on AquaMaps, enter genus “Neogobius” and species “melanostomus” to obtain a map showing their predicted spread.

map of Round Goby invasion in Europe


Because they are not tasty to humans it is hard to truly appreciate this fish from any perspective other than that of their successes as invaders. But to a larger, piscine predator they must indeed be tasty as they have become a substantial part of native gamefishes’ diet.  And for Lake Erie water snakes, as well as aquatic birds like gulls and cormorants, Round Gobies are a major new item on the menu.  Indeed, Round Gobies are so abundant in Lake Erie that frustrated anglers often complain that the pesky little perciforms are the only thing they can catch.

The Round Goby is here to stay, and changes wrought by their incursion will reverberate for decades across the Great Lakes at least. Have you caught one yet?


About the Author: Marc Kibbey is Associate Curator of the Fish Division at the Museum of Biological Diversity.

Am I or Am I Not a Dinosaur? Skull Identification Quiz

Do you love dinosaurs? Many of us grew up in the shadow of Jurassic Park Mania, and went through a dino-crazed phase during our childhood. Still, can you identify a dinosaur when you see one? There seems to be a lack of public awareness of what is actually classified under the label of Dinosauria.

Test your knowledge with this tetrapod skull ID quiz and check your answers below. The truth may surprise you! We would love to get comments from you. Which of these skulls is the most challenging?

1. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

2. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

3. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

4. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

5. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

6. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

7. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

8. Dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

9. And finally, dinosaur or not a dinosaur?

(Image Source: G Terrell 2016)

(all photos are by G Terrell 2016)



1) Yes! This is the skull of Herrerasaurus ischigualastensis. Herrerasaurus was an early theropod dinosaur from the late Triassic period, and one of the first predatory dinosaurs. (Image Credit:


2) No! This meter-long skull is from the living crocodilian, Gavialis gangeticus, or gharial. Gharials can be easily distinguished from crocodiles and alligators by their incredibly thin jaws, which are  an adaptation for catching fish.

(Image credit:


3) Yes! This skull is from the Keel-billed Toucan (Ramphastos sulfuratus), a colorful Latin American member of the toucan family Ramphastidae. Living birds comprise the only extant members of the dinosaur family tree. Dinosaurs are not really extinct at all, there are approximately 10,000 species of living birds. Keel-billed Toucans may seem to have cumbersome bills, but they are surprisingly lightweight and useful for thermoregulation.

The closely related Chestnut-mandibled Toucan Ramphastos swainsonii (Credit: G. Terrell 2016)


4) No! This skull belongs to the early synapsid of the Permian period, Dimetrodon. Dimetrodon is often (mistakenly) labeled as a dinosaur in the popular media. In fact, Dimetrodon is a member of the lineage that eventually lead to mammals. So, as mammals, we humans are far closer relatives of Dimetrodon, than Dimetrodon is of any dinosaur.

(Image credit:

5) Yes! This skull is from the late Jurassic dinosaur, Archaeopteryx . Often recognized as the “first bird,” Archaeopteryx was actually just one of many feathered, fluffy, winged dinosaurs that flitted around the forests of the Jurassic. Though probably not as well as modern birds, it is thought that Archaeopteryx was capable of briefly-sustained flight.

(Image credit:

6) No! This is the skull of the rhinoceros iguana (Cyclura cornuta), a species of lizard in the family Iguanidae. Rhinoceros iguanas live on the island of Hispaniola, where they can reach up to 54 inches in length.

(Image Credit:

7) No! This skull is the skull of a Komodo dragon, Varanus komodoensis, a species of lizard in the monitor lizard family Varanidae. Komodo dragons are the largest living lizards. They reach lengths of up to 10 feet! These large lizards have been known to prey upon water buffaloes.

(Image source:

8) Yes! This is the skull of the Great Hornbill, Buceros bicornis. Great hornbills are large, mostly frugivorous birds of South Asia in the family Bucerotidae. Like many extinct dinosaurs, hornbills possess seemingly-bizarre head ornamentation that is only present in adult individuals.

(Image credit:

9) Yes! This skull belongs to the famous Velociraptor mongoliensis. This late cretaceous predator, made famous by the Jurassic Park franchise, was a member of the Dromaeosauridae. This family of dinosaurs is extremely closely related to birds. All members of this family were fully feathered, possessed wings, and would have appeared to be “weird birds with teeth and tails.”

(A Velociraptor with prey. Image source:


GTerrellAbout The Author: Grant Terrell is a second year student in Evolution and Ecology at The Ohio State University. He works as a research assistant in the Tetrapod Collection at The Museum of Biological Diversity.