<h2>Deductive Reasoning to Understand the Past</h2>
<p>Deductive <a href="https://app.ulearngo.com/tutorials/introducing-study-of-life/scientific-reasoning">reasoning</a> combines the use of evidence and theories to make deductions about the past. Therefore scientists use their understanding of <a data-lesson="continental-drift" data-subject="biology" data-tutorial="history-of-life" href="https://app.ulearngo.com/biology/history-of-life/continental-drift">continental drift</a> and <a data-lesson="natural-selection-2" data-subject="biology" data-tutorial="evolution-overview" href="https://app.ulearngo.com/biology/evolution-overview/natural-selection-2">natural selection</a> theories, together with evidence of <a data-lesson="climate-and-weather" data-subject="biology" data-tutorial="ecology-biosphere" href="https://app.ulearngo.com/biology/ecology-biosphere/climate-and-weather">climate</a> changes and extinct organisms from the fossil record, to piece together Earth's history.</p>
<ul>
<li>Scientists use the fossil record to make conclusions about the <a data-lesson="history-of-life" data-subject="biology" data-tutorial="evolution-overview" href="https://app.ulearngo.com/biology/evolution-overview/history-of-life">history of life</a> through a process of <strong>deductive reasoning</strong>.</li>
<li>Deductive reasoning involves combining our understanding of known principles to make conclusions about new evidence that we have uncovered.</li>
<li>Our knowledge of the history of life is not based on radiometric <a data-lesson="methods-of-dating-fossils" data-subject="biology" data-tutorial="history-of-life" href="https://app.ulearngo.com/biology/history-of-life/methods-of-dating-fossils">dating</a> methods alone. Rather, our understanding of the changes in Earth's climate and <a data-lesson="biogeography-2" data-subject="biology" data-tutorial="ecology-biosphere" href="https://app.ulearngo.com/biology/ecology-biosphere/biogeography-2">biogeography</a> allow us to make conclusions about newly discovered fossil evidence.</li>
<li>For example, from our knowledge of the changes to the Earth's early atmosphere, we know that the formation of the <a data-lesson="air-pollution" data-subject="biology" data-tutorial="ecology-overview" href="https://app.ulearngo.com/biology/ecology-overview/air-pollution">ozone</a> layer blocked off the damaging rays of the sun's UV rays. This led to the <a data-lesson="population-growth-patterns" data-subject="biology" data-tutorial="ecology-overview" href="https://app.ulearngo.com/biology/ecology-overview/population-growth-patterns">growth</a> of <a data-lesson="summarizing-asexual-reproduction" data-subject="biology" data-tutorial="plant-reproduction" href="https://app.ulearngo.com/biology/plant-reproduction/summarizing-asexual-reproduction">plant</a> <a data-lesson="summarizing-community-ecology" data-subject="biology" data-tutorial="population-community-ecology" href="https://app.ulearngo.com/biology/population-community-ecology/summarizing-community-ecology">species</a> which gradually made terrestrial existence possible.</li>
<li>
<p>A transitional fossil is any fossilised remains that is common to an ancestral life form as well as to the group that is derived from it.</p>
</li>
<li>
<p>Transitional <a data-lesson="fossils" data-subject="biology" data-tutorial="evolution-overview" href="https://app.ulearngo.com/biology/evolution-overview/fossils">fossils</a> give us information about how an ancestral species evolved to form the existing species.</p>
</li>
<li>
<p>An example of a transitional fossil is the <em>Archaeopteryx</em>. It is thought to belong to the genus of Theropod dinosaur which is closely related to the birds.</p>
</li>
</ul>
<h2 class="title">Comparing the skeleton of a modern bird (chicken) to the Archaeopteryx</h2>
<p>We will use the pictures below to compare the <a data-lesson="skeletons" data-subject="biology" data-tutorial="animal-systems-intro" href="https://app.ulearngo.com/biology/animal-systems-intro/skeletons">skeletons</a> of a dinosaur (Theropod), <em>Archaeopteryx</em> and a chicken (modern bird).</p>
<div class="wp-caption alignleft" id="attachment_122410" style="width: 800px"><a href="https://data.ulearngo.com/assets/6e519181-c619-4a53-863a-d306f242e5c4"><img alt="theropod-skeleton" class="size-full wp-image-122410" height="485" src="https://data.ulearngo.com/assets/6e519181-c619-4a53-863a-d306f242e5c4" width="800"/></a><p class="wp-caption-text">Skeleton of a dinosaur (Theropod)</p></div>
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<section>
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</section>
<div class="wp-caption alignnone" id="attachment_122411" style="width: 400px"><a href="https://data.ulearngo.com/assets/11c4d773-55d4-479e-abcb-e77b9a9d3837"><img alt="Archaeopteryx-skeleton" class="size-full wp-image-122411" height="412" src="https://data.ulearngo.com/assets/11c4d773-55d4-479e-abcb-e77b9a9d3837" width="400"/></a><p class="wp-caption-text">Skeleton of Archaeopteryx</p></div> <div class="wp-caption alignnone" id="attachment_122413" style="width: 800px"><a href="https://data.ulearngo.com/assets/2a6d95cc-a51f-4945-a7be-644e5fcb579a"><img alt="" class="size-full wp-image-122413" height="1157" src="https://data.ulearngo.com/assets/2a6d95cc-a51f-4945-a7be-644e5fcb579a" width="800"/></a><p class="wp-caption-text">Skeleton of a chicken (modern bird)</p></div>
<section>
<table>
<tbody>
<tr>
<td colspan="2">
<h3><strong>Archaeopteryx vs Dinosaur:</strong></h3>
<p>SIMILARITIES:</p>
</td>
</tr>
<tr>
<td colspan="2">1. Jaws have teeth</td>
</tr>
<tr>
<td colspan="2">2. Hand / arm has claws</td>
</tr>
<tr>
<td colspan="2">3. Long bony tail present</td>
</tr>
<tr>
<td colspan="2">4. Presence of gastralia or dermal ribs (not attached to spine)</td>
</tr>
<tr>
<td colspan="2">
<h3><strong>Archaeopteryx vs Dinosaur:</strong></h3>
<p>DIFFERENCES:</p>
</td>
</tr>
<tr>
<td>1. Long forelimbs, like wings</td>
<td>Short forelimbs</td>
</tr>
<tr>
<td>2. Feathers present</td>
<td>No feathers</td>
</tr>
<tr>
<td>3. Hand has three claws</td>
<td>Hand has five claws</td>
</tr>
<tr>
<td>4. Furcula / wish <a data-lesson="bone" data-subject="biology" data-tutorial="musculoskeletal-system" href="https://app.ulearngo.com/biology/musculoskeletal-system/bone">bone</a> present</td>
<td>No furcula present</td>
</tr>
<tr>
<td colspan="2">
<h3><strong>Archaeopteryx vs Modern bird</strong></h3>
<p>SIMILARITIES:</p>
</td>
</tr>
<tr>
<td colspan="2">1. Feathers are present</td>
</tr>
<tr>
<td colspan="2">2. Forelimbs are long and wing-like</td>
</tr>
<tr>
<td colspan="2">3. Furcula / wish bone present (fused clavicles)</td>
</tr>
<tr>
<td colspan="2">4. Bones of the lower forelimb are separate</td>
</tr>
<tr>
<td colspan="2">
<p><strong>Archaeopteryx vs Modern bird</strong></p>
<p>DIFFERENCES:</p>
</td>
</tr>
<tr>
<td>1. Teeth in jaws</td>
<td>No teeth in the beak</td>
</tr>
<tr>
<td>2. Claws on forelimbs</td>
<td>Forelimbs without claws</td>
</tr>
<tr>
<td>3. Long bony tail</td>
<td>Short tail <a data-lesson="bones" data-subject="biology" data-tutorial="animal-systems-intro" href="https://app.ulearngo.com/biology/animal-systems-intro/bones">bones</a> / pygostral present</td>
</tr>
<tr>
<td>4. No breast bone</td>
<td>Breast bone with a keel</td>
</tr>
</tbody>
</table>
</section>

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Deductive Reasoning to Understand the Past

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Deductive Reasoning to Understand the Past

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