Crocodiles and trees – two iconic organisms that have coexisted on Earth for hundreds of millions of years. But which group is older? At first glance, huge, ancient trees seem timeless. Yet crocodiles have a key advantage: as reptiles, they evolve slower than trees.
If you’re short on time, here’s a quick answer: yes, crocodiles as a group are older than trees, with crocodilian ancestors arising at least 80 million years before the first forests. Now let’s dive deeper into the evolutionary history and uncover the evidence behind this fascinating question.
In this article, we’ll trace the origins of crocodiles and trees, examining key fossils and evolutionary events. We’ll learn how crocodiles and their ancestors survived mass extinctions while forests rose and fell.
And we’ll reflect on what the greater age of crocodiles reveals about longevity, adaptation, and our ever-changing Earth.
The Rise of Crocodilians
Originating in the Late Triassic
Crocodilians first emerged around 200 million years ago during the Late Triassic period. The earliest crocodilian fossils date back to around 230 million years ago in the form of Protosuchus and other early crocodylomorphs.
These primitive ancestors already showed some of the hallmark features of modern crocodilians including the elongated snout and armored back and tail. However, they were much smaller in size, averaging only 1-2 meters long compared to the 5-7 meter monsters we see today.
By the Jurassic period around 150 million years ago, crocodilians had diversified into three major lineages – the slender, land-dwelling sphenosuchians, the semi-aquatic metriorhynchids, and the more crocodile-like teleosaurids.
The teleosaurids gave rise to the first truly aquatic forms resembling modern species. With their powerful tails, webbed feet, and ability to hold their breath underwater, these crocs were well-adapted for an aquatic lifestyle hunting fish and other prey.
Distinct Features of Early Crocodilians
Some key features that distinguish early crocodilians from other archosaurs (bird-hipped reptiles) include:
- Secondary bony palate – Allowed them to breathe while holding prey underwater
- Powerful jaw muscles and teeth – For delivering bone-crushing bites
- Salt glands – To excrete excess salt from living in marine environments
- Armored skin – Bony scutes (scales) covering the back and tail
- Powerful tails – To propel through water when swimming
These adaptations suited crocodilians perfectly for semi-aquatic ambush predation. By staying perfectly still in the water while concealing most of their body, they could strike out suddenly and drag prey underwater with extreme force.
Surviving the Mass Extinctions
Crocodilians were among the survivors after the mass extinction events that wiped out the dinosaurs around 65 million years ago. Their resilience is largely thanks to some key advantages:
- Ability to slow down metabolism and go months without eating
- Minimal energy requirements due to ectothermic physiology (cold-blooded)
- Armored hide and tolerance for anoxic environments when hibernating underwater
- Versatile amphibious lifestyle allowing them to hunt in water and on land
While many other archosaurs like pterosaurs and non-avian dinosaurs died out, the earliest crocodilians were able to hang on and eventually flourish in the Cenozoic era. Today there are 25 crocodilian species including crocodiles, alligators, caimans, and gharials still going strong after 200 million years!
When Did Trees First Appear?
The evolution of trees and forests is an amazing story spanning hundreds of millions of years. While the exact origin of trees is difficult to pinpoint, most evidence suggests primitive tree-like plants emerged around 385 million years ago in the Devonian period.
Since then, forests have continued to evolve and diversify, weathering ice ages and mass extinctions to become the diverse ecosystems we know today.
The Evolution of Forests
During the Devonian period, shrub-like plants called progymnosperms were some of the first plants to develop wood-like tissues that allowed them to grow tall. But these primitive “trees” were more like woody vines or shrubs compared to modern trees.
True trees with extensive height and branching likely emerged in the Carboniferous period around 300 million years ago.
By the Permian period nearly 300 million years ago, massive forests dominated by conifers flourished across the supercontinent Pangea. But a mass extinction event 252 million years ago known as “The Great Dying” wiped out over 90% of all species, decimating these primordial forests.
From the ashes, new types of cone-bearing trees evolved and radiated during the Triassic period re-establishing forests once again.
Diversification in the Cretaceous
During the Cretaceous period 145-66 million years ago, flowering plants emerged and diversified. This allowed angiosperm trees like magnolias, maples, oaks and palms to populate forests alongside conifers.
The Cretaceous saw an explosion of diversity in tree species that laid the foundations for modern forests.
Interestingly, some Cretaceous tree species like ginkgo trees and dawn redwoods still exist today as “living fossils”. This highlights the success and resilience of these ancient tree lineages that have survived over 100 million years into the modern era.
Mass Extinctions Allowed Forests to Spread
The meteor impact that killed the dinosaurs 66 million years ago triggered another huge mass extinction. With the giant dinosaurs gone, mammals and birds diversified to fill newly vacated niches. This allowed forests to expand their range into new areas previously suppressed by massive dinosaur herbivory.
During ice ages over the last 2.6 million years, forests contracted into small refugia. But interglacial periods allowed forests to spread once again. Modern day forests represent the accumulated survivors of hundreds of millions of years of evolution, extinction, and regeneration.
Comparing the Evolutionary History
Reptiles Evolve More Slowly Than Plants
Reptiles like crocodiles tend to evolve at a much slower pace than plants. While plants evolve relatively quickly to adapt to changing environments, reptiles are characterized by slow rates of molecular evolution. Their morphological changes generally occur gradually over millions of years.
For instance, today’s crocodiles look very similar to crocodiles from 150 million years ago. In contrast, flowering plants emerged only 130 million years ago and have since diversified into over 300,000 species.
Persistence Through Changing Climates
The slow rate of evolution allows reptiles like crocodiles to persist through changing climates. Crocodiles have survived ice ages, hothouse climates, and mass extinction events with little morphological change.
Their adaptations like heat exchange mechanisms and salt secreting glands enable them to thrive in diverse environments. In fact, crocodiles are considered living fossils – their bodies resembling extinct species.
While many organisms go extinct due to climate change, crocodiles have exhibited resilience for 200 million years. Their longevity reveals that slow evolution can be advantageous for survival.
What Crocodilian Longevity Reveals
The incredible longevity of crocodilians reveals that evolution does not always favor specialization. Generalist species that can adapt to wide conditions through behavioral plasticity tend to have greater longevity in the fossil record.
For instance, crocodiles have very generalized diets, eating diverse prey items from fish to mammals. Their flexible mating patterns also enable breeding in changing environments. Additionally, crocodiles do not expend extra energy on costly features like huge antlers or tusks.
Rather, crocodilians demonstrate that conservation of simple adaptive traits enables survival through dynamic Earth history.
Conclusion
The longer evolutionary history of crocodilians compared to trees highlights crucial differences between these two familiar organisms. As reptiles, crocodilians evolve relatively slowly, allowing them to persist for 200 million years.
Trees, as plants, evolved more rapidly – yet both groups survived sweeping changes to Earth’s climate and landscapes.
The antiquity of crocodiles contains lessons about resilience, longevity, and humanity’s place in nature. As iconic denizens of swamps, lakes, and rivers, crocodiles remind us that we share this planet with other species whose histories run far deeper than our own.
