Author Archives: Greg

Sore-mouthed dinosaurs

Benjamin Franklin quipped that the only thing in this world that is certain is death and taxes. He could have added disease to that list too.

There is a growing body of evidence that many of the diseases that humans and animals suffer from have followed us around from our earliest evolutionary roots. And recognizing disease in fossil animals can tell us a great deal about how the animals lived and give us insight into their everyday lives.

Take for example the well-known dinosaur specimen popularly called “Sue,” one of the most complete Tyrannosaur rex specimens known. Casts of its skeleton have been traveling to museums for many years in the exhibit “A T. rex named Sue,” amazing many people with its size and majesty. In the last weeks of Sue’s life she may have been a very cranky Dame indeed.

Upon viewing her skeleton, many have noticed the unusual holes along her left jaw. Those holes are not normal, but where they a sign of trauma, like wounds from combat? Turns out they are likely from a much small foe than another T. rex.

Left jaw of the dinosaur Sue showing pathologic holes

Left jaw of the dinosaur Sue showing pathologic holes

In a recent article (Wolff et al., 2009) researchers suspect that Sue, and other large carnivorous dinosaurs like her, were plagued by an infection of something like Trichomonas gallinae, a pear-shaped protozoan parasite that today infects birds. The parasite lives in the upper digestive tract of many bird species and causes sores in the mouth and throat. Some of the sores in modern birds have caused bone erosion that looks just like that seen in Sue.

Modern birds transmit the disease through discharge of body fluids. (This parasite does not attack humans). Adult birds that feed offspring can infect them directly for example. Infection is very common in modern birds, and infected birds may have no ill effects. It is not unlikely that in 65 million years of coevolution modern birds have built up resistance to the disease that their ancient cousins, the meat-eating dinosaurs, did not have.

It appears that Sue, and others like her, died of simple starvation, not being able to eat because of mouth and throat sores. An ignoble end perhaps, but showing that this thing we call life can change on the smallest circumstances.

WOLFF, E. D. S., S. W. SALISBURY, J. R. HORNER, AND D. J. VARRICCHIO. 2009. Common Avian Infection Plagued the Tyrant Dinosaurs. Plos One, 4(9):e7288.

Other dinosaur facts can be found here at Boneblogger. Search or select the category for more.

Musk ox say no to hunting

As we face the uncertain effects of climate change ourselves in the future it is instructive to look back in time to see how other species fared. (See also a geologic perspective on the effects of climate change.) Paleontology is one of the main sciences involved in this research and so proves to be very relevant to this modern issue.

A recurring mystery in paleontology is the cause of the most recent major extinction event at the end of the Pleistocene or Ice Age. Many large species of mammals, collectively referred to as megafauna, became extinct relatively recently, a mere 10,000 years ago more or less. Charismatic animals such as mammoths, mastodons, giant ground sloths, and saber toothed cats vanished from the Earth forever.

It has long been debated what the primary cause of this extinction event was. Just as with other major extinctions observed in the fossil record, there are a number of suspected causes for Ice Age extinctions: disease, climate changes, and extra-terrestrial phenomena like asteroids. But the Ice Age extinctions have another factor that previous extinction events do not have—the emergence of humans as a major player upon the landscape. Did human activities, maybe the over hunting of the megafauna, drive them to extinction?

Many studies have tried to get at this question, but it is very difficult to separate all the confounding issues from each other to focus on just one to test its potential effects. A new study however was able to do just this.

In a recent paper (Campos et al., 2010) DNA material was extracted and analyzed from one of the species that did survive the Ice Age extinctions, the musk oxen. This Ice Age relic lives today mainly in the high-latitudes of Greenland and Canada, but was once more wide-spread. Indeed, its remains have even found as far south as Nebraska, New York, and Ohio during the Pleistocene.

Musk oxen are well adapted to the extremes of arctic living with sturdy bodies and thick coats of hair.

Musk oxen are well adapted to the extremes of arctic living with sturdy bodies and thick coats of hair.

The researchers collected samples from across the musk oxen’s former range for the last 60,000 years. They examined the DNA to look for patterns of population dynamics over that period. Basically, when a population is strong and has many members the DNA samples show an increase in diversity—more genetic variation in the mix. When populations suffer and numbers decrease the results show up in the DNA as a decrease in diversity, sometimes referred to as a genetic bottleneck. So, the DNA diversity over time shows a proxy for population numbers and health.

Therefore, if humans were a prime driver of population declines for musk oxen at the end of the Ice Age we would expect to see genetic bottlenecks within the DNA corresponding to the timing of human activity within the musk oxen’s range.

The DNA results show that the geographic origin of all the musk oxen DNA is northeast Siberia with a large diverse population. However, the population in that region crashed about 45,000 years ago. After that population decline, there was a world-wide genetic diversity increase about 30,000 years, followed by another decline about 18,000 years ago, and finally a slight recovery about 5,000 years to the modern relict populations.

With these data we can directly test for the first time the correlation of population declines of the musk ox with human activity. And, in fact, they do not correlate very well, suggesting that humans played little role in the population dynamics of musk oxen.

So, if not humans, what then was driving the populations to decline?  The most likely cause was environmental changes, particularly climate changes. The Pleistocene is characterized by shifts in climate patterns with the best-known effect being glacial advance and retreat over the last 2 million years. It seems, at least in the case of musk oxen populations, that the pattern of boom and bust was driven by their ability to adapt to climatic changes in their environment. Musk oxen almost went the way of the mammoths and succumbed fully to extinction, but managed to just hold on by their horns in greatly reduced numbers until today.

Of course, whether they, or any other species that are similarly at risk, will weather the next several decades, and any modern climate changes, remains to be seen. The effects of climate change may well prove to be too much for them after all.

CAMPOS, P. F., E. WILLERSLEV, A. SHER, L. ORLANDO, E. AXELSSON, A. TIKHONOV, K. AARIS-SØRENSEN, A. D. GREENWOOD, R.-D. KAHLKE, P. KOSINTSEV, T. KRAKHMALNAYA, T. KUZNETSOVA, P. LEMEY, R. MACPHEE, C. A. NORRIS, K. SHEPHERD, M. A. SUCHARD, G. D. ZAZULA, B. SHAPIRO, AND M. T. P. GILBERT. 2010. Ancient DNA analyses exclude humans as the driving force behind late Pleistocene musk ox (Ovibos moschatus) population dynamics. Proceeding of the National Academy of Sciences.

Keep Your Cichlids Healthy – It’s Easy

Guest Post

The hobby of keeping cichlids can be a very enjoyable and rewarding experience. Most people just getting started in keeping these very intelligent aquarium fish have lots of questions. Even as an experienced aquarist, I seem to learn something new everyday. Here are some tips to get you started.

The first thing that you need to do when keeping cichlids is to consider what size that your cichlids will be when they are fully mature. If you have gotten bitten by the Oscar bug and have fallen in love with these very personable fish, you are simply going to need a large tank.

Most people will recommend at least a 55 gallon aquarium to keep a pair of Oscar fish. That is simply the bare minimum for these big guys. If you have a smaller variety, you just need a smaller tank. Simple, right?

Second, ph level and water salinity, among other water chemistry levels, can be very different between the different types of cichlids. Just consider African Cichlids. They are found in different lakes in Africa. Each of these lakes have their own unique water chemistry, so if you are keeping Africans, it is very important to do your research if you are going to replicate their native habitat.

If your cichlids are going to thrive, whether they are African or New World Cichlids, temperature and water chemistry must be monitored.

Plants and cichlids sometimes just do not match well. Many cichlids are very intelligent, but they love to make lettuce out aquarim plants. Its a challenge, but it can be done.

American varieties of cichlids seem to be able to tolerate plants in their aquarium better that Africans do. But having made that point, Oscars love to destroy plant life. Angel fish, on the other hand, seem to tolerate plants very well.

Angel fish can be some of the most enjoyable cichlids in my opinion. They even do very well in community tanks because they are generally docile and tolerate plants very well.

Visit cichlid care to learn how to keep cichlids healthy, colorful and happy. And visit keeping cichlids to learn how to keep your cichlids stress free.

A Closer Look At A Diverse Brisbane

Guest Post

Brisbane, located in Australia, is much different then many of the tourists destination throughout the world. It offers a diversity in the available activities for one to enjoy, and it is all within a short distance to the center of the city. In the city, itself, you can enjoy a wonderful day shopping at some of the greatest stores around and dining at the many locales throughout. There are street side markets, local cuisine and talent spread out in this city area. When the night time comes rolling in the fun does not have to stop. There are a variety of clubs, shows and concerts for you to enjoy before you call it a day.

If you want to venture outside of Brisbane there is also much for you to see and do. There are fabulous beaches, great parks, thrilling amusement parks and incredible rain forests, all a short drive away. You can spend a day touring the local vineyards, talking a tour through the rain forest or having a picnic in the park.

One thing that everyone loves, about Brisbane, is the spectacular views that it offers. The views from Kangaroo Point and Story Bridge are like no other that you will ever witness. Let us also not forget about the cliffs that overlook the city, as they too offer some of the most breathtaking views anytime of the day.

The Moreton Bay area makes up one that’s unbelievably contrasting. It extends the unparalleled experiences of the Moreton Harbor and among Australia’s biggest marinas, then merely a scant ferryboat ride away you’ll witness the tender dunes of Moreton Island. This unbelievable island escape can be ideal for a day of four wheeling as well as dolphin watching or remain a couple of days at the astounding Tangalooma Resort or camping along the shore of this exquisite tropic island.

While visiting Brisbane you are also guaranteed that the weather will be perfect for the beach. Brisbane has year round moderate temperatures, which makes for a great escape when the colder months set in. There is such a diverse selection of activities and entertainment in Brisbane that you can be sure everyone will find something to enjoy.

There are numerous brisbane hotels that you can choose from while planning your Brisbane holiday. When you are ready to reserve your brisbane accommodation go to www.brisbaneinformation.com.au.

Complete Your Vacation By Scuba Diving in Hawaii

Guest Post

Some of the most popular activities on the beautiful Hawaiian islands are, surfing, scuba diving, snorkeling, and much much more. Scuba diving in Hawaii is one of the most popular things to do, and you shouldn’t skip out on it.

Hawaii has many companies which offer scuba diving tours. All of them have certified and professionally trained instructors. If you are brand new to scuba diving they will help you with the basics so that you can enjoy your tour. If you already have your certification, they can still take you out to some of the most popular dive spots.

Hawaii also offers the chance for you to get your certification while you are there. Most of the tour companies will help you get your certification while you are there.

Thanks to the warm waters surrounding the Hawaiian Islands, scuba diving is wonderful there. Some of the popular items you will be able to see are arches, lava tubes, and caverns. If you like to go on adventures, you can look for pygmy killer whales, whale sharks, and even spotted dolphins. But be sure to have a guide with you at all times.

Scuba diving can be a great experience for everyone. You can also take your kids on the scuba diving tours, the instructors will make sure everybody will enjoy the tour and be safe. Make sure you don’t forget your water proof camera to take pictures of the many fish.

Scuba diving tours are designed for a small group of people. The reason for this is so the instructors can have as much one on one time as possible, to make sure the tour is fun for everyone. There is no doubt that you will have a great time. Hawaii scuba diving is something that should be high on your do list, many of the things you will see you won’t have the chance to see them anywhere else.

Want to find out more about Hawaiian vacation reviews, then visitHawaii scuba diving tour reviews to help you choose the perfect scuba diving tour for your Hawaiian vacation.