UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 OMB APPROVAL OMB Number: 3235-0145 Expires: February 28, 2009 Estimated average burden hours per response 14.5

SCHEDULE 13D

Under the Securities Exchange Act of 1934
(Amendment No. 1)

Canadian Superior Energy, Inc.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

136644101

(CUSIP Number)

Ellyn Roberts, Esq.
Shartsis Friese LLP

One Maritime Plaza, 18^th Floor

San Francisco, California 94111

(415) 421-6500

(Name, Address and Telephone Number of Person
Authorized to Receive Notices and Communications)

September 30, 2008

(Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of sections 240.13d-1(e), 240.13d-1(f) or 140.13d-1(g), check the following box. [ ]

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See section 240.13d-7 for other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.

1. Names of Reporting Persons

Palo Alto Investors

2. Check the Appropriate Box if a Member of a Group (See Instructions)
(a)
(b) X

3. SEC Use Only

4. Source of Funds (See Instructions) AF

5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) ____

6. Citizenship or Place of Organization California

Number of Shares Beneficially Owned by Each Reporting Person With	7. Sole Voting Power 0
	8. Shared Voting Power 16,002,500
	9. Sole Dispositive Power 0
	10. Shared Dispositive Power 16,002,500

11. Aggregate Amount Beneficially Owned by Each Reporting Person 16,002,500

12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See
Instructions)

13. Percent of Class Represented by Amount in Row (11) 10.1%

14. Type of Reporting Person (See Instructions) CO, HC

1. Names of Reporting Persons

Palo Alto Investors, LLC

2. Check the Appropriate Box if a Member of a Group (See Instructions)
(a)
(b) X

3. SEC Use Only

4. Source of Funds (See Instructions) AF

5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) ____

6. Citizenship or Place of Organization California

Number of Shares Beneficially Owned by Each Reporting Person With	7. Sole Voting Power 0
	8. Shared Voting Power 16,002,500
	9. Sole Dispositive Power 0
	10. Shared Dispositive Power 16,002,500

11. Aggregate Amount Beneficially Owned by Each Reporting Person 16,002,500

12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See
Instructions) ______

13. Percent of Class Represented by Amount in Row (11) 10.1%

14. Type of Reporting Person (See Instructions) IA, OO

1. Names of Reporting Persons

William Leland Edwards

2. Check the Appropriate Box if a Member of a Group (See Instructions)
(a)
(b) X

3. SEC Use Only

4. Source of Funds (See Instructions) AF

5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) ____

6. Citizenship or Place of Organization _______

Number of Shares Beneficially Owned by Each Reporting Person With	7. Sole Voting Power 50,000
	8. Shared Voting Power 16,002,500
	9. Sole Dispositive Power 50,000
	10. Shared Dispositive Power 16,002,500

11. Aggregate Amount Beneficially Owned by Each Reporting Person 16,052,500

12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See
Instructions) ______

13. Percent of Class Represented by Amount in Row (11) 10.1%

14. Type of Reporting Person (See Instructions) IN, HC

1. Names of Reporting Persons

Anthony Joonkyoo Yun, MD

2. Check the Appropriate Box if a Member of a Group (See Instructions)
(a)
(b) X

3. SEC Use Only

4. Source of Funds (See Instructions) AF

5. Check if Disclosure of Legal Proceedings Is Required Pursuant to Items 2(d) or 2(e) ____

6. Citizenship or Place of Organization U.S.A.

Number of Shares Beneficially Owned by Each Reporting Person With	7. Sole Voting Power 0
	8. Shared Voting Power 16,002,500
	9. Sole Dispositive Power 0
	10. Shared Dispositive Power 16,002,500

11. Aggregate Amount Beneficially Owned by Each Reporting Person 16,002,500

12. Check if the Aggregate Amount in Row (11) Excludes Certain Shares (See
Instructions) ______

13. Percent of Class Represented by Amount in Row (11) 10.1%

14. Type of Reporting Person (See Instructions) IN, HC

Item 1. Security and Issuer

This statement relates to shares of Common Stock (the "Stock") of Canadian Superior Energy, Inc. (the "Issuer"). The principal executive office of the Issuer is located at Suite 3200, 500 - 4th Avenue SW, Calgary, Alberta, Canada, T2P 2V6.

Item 2. Identity and Background

The persons filing this statement and the persons enumerated in Instruction C of Schedule 13D and, where applicable, their respective places of organization, general partners, directors, executive officers and controlling persons, and the information regarding them, are as follows:

(a) William Leland Edwards, Palo Alto Investors, LLC ("PAI LLC"), Palo Alto Investors ("PAI Corp") and Anthony Joonkyoo Yun, MD (collectively, the "Filers").

(b) The business address of the Filers is:

470 University Avenue, Palo Alto, CA 94301

(c) Present principal occupation or employment or the Filers and the name, principal business and address of any corporation or other organization in which such employment is conducted:

PAI LLC is an investment adviser registered with the Securities and Exchange Commission and is the general partner of, and investment adviser to, investment limited partnerships. The sole manager of PAI LLC is PAI Corp. Mr. Edwards is the president and controlling shareholder of PAI Corp and the controlling owner of PAI LLC. Mr. Yun is the president of PAI LLC.

(d) During the last five years, none of the Filers has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e) During the last five years, none of the Filers was a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

(f) Mr. Edwards and Mr. Yun are United States citizens.

Item 3. Source and Amount of Funds or Other Consideration

The source and amount of funds used in purchasing the Stock were as follows:

Purchaser	Source of Funds	Amount
PAI LLC	Funds Under Management	$38,027,707

Item 4. Purpose of Transaction

The Filers acquired the Stock for investment purposes. On September 29, 2008, Greg Noval sent a letter to Palo Alto Investors on behalf of the Issuer's Board of Directors responding to a letter from Palo Alto Investors sent earlier in the day, and Palo Alto Investors sent a further response to the Board. A copy of that correspondence is attached hereto as Exhibit B.

In pursuing their investment purposes, the Filers may further purchase, hold, vote, trade, dispose of, engage in option, swap or other derivative securities transactions with respect to or otherwise deal in the Stock at times, and in such manner, as they deem advisable to benefit from changes in the Stock's market price, and changes in the Issuer's operations, business strategy or prospects. To evaluate such alternatives, the Filers routinely will monitor the Issuer's operations, prospects, business development, management, competitive and strategic matters, capital structure and prevailing market conditions, the Filers' liquidity requirements and other investment considerations. Consistent with their investment research methods and evaluation criteria, the Filers may discuss such matters with the Issuer's management, Board of Directors, other shareholders, industry analysts, existing or potential strategic partners or competitors, investment and financing professionals, sources of credi t and other investors. Such factors and discussions may affect materially, and result in, the Filers' modifying their ownership of the Stock or exchanging information with the Issuer pursuant to appropriate confidentiality or similar agreements. The Filers may reconsider and change their plans or proposals relating to the Stock at any time.

Item 5. Interest in Securities of the Issuer

(a), (b), (d) Each Filer's beneficial ownership of the Stock on the date of this report is reflected on that Filer's cover page. PAI LLC is an investment adviser with the power to invest in, vote and dispose of the Stock on behalf of its clients. Its clients have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Stock. No client individually holds more than 5% of the outstanding Stock. Mr. Edwards is the president and controlling shareholder of PAI Corp., which is the sole manager of PAI LLC, and is the controlling owner of PAI LLC. Mr. Yun is the president of PAI LLC. The Filers are filing this Schedule 13D jointly, but not as members of a group, and each of them expressly disclaims membership in a group. Each Filer disclaims beneficial ownership of the Stock except to the extent of that Filer's pecuniary interest therein.

(c) There were no transactions in the Stock by the Filers since this Schedule 13D was last filed.

Item 6. Contracts, Arrangement, Understandings or Relationships with Respect to Securities of the Issuer

PAI LLC is the general partner of investment partnerships pursuant to agreements of limited partnership that grant to PAI LLC the authority, among other things, to invest the funds of such investment partnerships in the Stock, to vote and dispose of the Stock and to file this statement on behalf of such investment partnerships Pursuant to such agreements, PAI LLC is entitled to allocations based on assets under management and realized and unrealized gains.

In addition, 750,000 shares of the Stock are represented by warrants, the form of which is incorporated by reference in this Schedule 13D as Exhibit C. In addition, those warrants are governed by and subject to the terms of a Securities Purchase Agreement and Registration Rights Agreement, the forms of which are incorporated by reference to this Schedule 13D as Exhibits D and E.

Item 7. Material to Be Filed as Exhibits

Exhibit A Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G
Exhibit B Correspondence between the Issuer's Board of Directors and Palo Alto Investors
Exhibit C Form of Warrant to Purchase Shares of Common Stock, incorporated by reference to the Issuer's Form F-3 filed September 26, 2008Exhibit D Form of Securities Purchase Agreement, incorporated by reference to the Issuer's Form F-3 filed September 26, 2008
Exhibit E Form of Registration Rights Agreement, incorporated by reference to the Issuer's Form F-3 filed September 26, 2008

SIGNATURES

After reasonable inquiry and to the best of my knowledge, I certify that the information set forth in this statement is true, complete and correct.

Dated: September 30, 2008

PALO ALTO INVESTORS By: /s/ Mark Shamia, Chief Operating Officer	PALO ALTO INVESTORS, LLC By: /s/ Mark Shamia, Chief Operating Officer
/s/ Anthony Joonkyoo Yun, MD	/s/ William Leland Edwards

EXHIBIT A

AGREEMENT REGARDING JOINT FILING

OF STATEMENT ON SCHEDULE 13D OR 13G

The undersigned agree to file jointly with the Securities and Exchange Commission (the "SEC") any and all statements on Schedule 13D or Schedule 13G (and any amendments or supplements thereto) required under section 13(d) of the Securities Exchange Act of 1934, as amended, in connection with purchases and sales by the undersigned of the securities of any issuer until such time as the undersigned file with the SEC a statement terminating this Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G. For that purpose, the undersigned hereby constitute and appoint Palo Alto Investors, LLC, a California limited liability company, as their true and lawful agent and attorney-in-fact, with full power and authority for and on behalf of the undersigned to prepare or cause to be prepared, sign, file with the SEC and furnish to any other person all certificates, instruments, agreements and documents necessary to comply with section 13(d) and section 16(a) of the Securities Exchange Act o f 1934, as amended, in connection with said purchases and sales, and to do and perform every act necessary and proper to be done incident to the exercise of the foregoing power, as fully as the undersigned might or could do if personally present, until such time as the undersigned file with the SEC a statement terminating this Agreement Regarding Joint Filing of Statement on Schedule 13D or 13G.

Dated: September 29, 2008

PALO ALTO INVESTORS By: /S/ Mark Shamia, Chief Operating Officer	PALO ALTO INVESTORS, LLC By: /S/ Mark Shamia, Chief Operating Officer
/S/ Anthony Joonkyoo Yun, MD	/S/ William Leland Edwards

EXHIBIT B

From: Greg Noval

Sent: Monday, September 29, 2008 9:02 PM

To: David Anderson

Subject: Re: Palo Alto Investor's Letter to Canadian Superior dated September 29, 2008

Importance: High

To: Palo Alto Investors

Further to our discussions of this evening and after receiving your letter of today's date outlining your concerns about potential conflicts of interests between Canadian Superior Energy Inc. ("Canadian Superior") and Challenger Energy Corp. ("Challenger Energy") and certain directors and management thereof, on behalf of Canadian Superior, I would like to confirm that several items were discussed with representatives of your firm which we believe mitigate or eliminate any perceived conflicts and/or management issues.

The Board of Directors of Canadian Superior established today a special committee comprised of three (3) independent directors to review, recommend and/or approve any future transactions between Canadian Superior and Challenger Energy. This is in addition to normal requirements under corporate law which Canadian Superior has followed.

Additionally, in any Board matter where the Chairman or any other Director has a conflict, he has and will continue to recuse himself from voting on the issue. Accordingly, we feel that given the above mentioned and the other important matters discussed with you, we have resolved the differences outlined in your letter. However, we will be having further discussions with you to keep you fully apprised of any future developments between the two companies through the independent committee which you are welcome to meet with at any time.

We apologize for any miscommunication that may have led you to believe that these perceived conflicts or issues raised in your letter were irreconcilable and we look forward to meeting with you regarding any issues you may have in the future.

We appreciate your support and look forward to continuing our long-term relationship with your firm.

Yours truly,

CANADIAN SUPERIOR ENERGY INC.

Greg Noval

Chairman

From: David Anderson

Sent: Monday, September 29, 2008 9:12 PM

To: 'Greg Noval Personal'

Subject: RE: Palo Alto Investor's Letter to Canadian Superior dated September 29, 2008

To the Board of Directors of Canadian Superior,

Thank you for your letter today outlining the discussions occurring between representatives of our firm and yours this evening. We find your response in keeping with our desires to resolve our outstanding corporate governance concerns. We appreciate that you have taken steps to ensure independent review of transactions occurring between Challenger Energy, Inc. and Canadian Superior Energy, Inc. and while we agree that this is a key step, we will continue to monitor the situation. We would like to accept your offer to meet with your independent Directors and committee members to review the overall transactional approval process regarding any future strategic or financial transactions between the two companies. Given the changes you have made and have committed to make, we consider this matter resolved.

Sincerely,

Palo Alto Investors

David Anderson

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